There is just about nothing ripped straight from Echoes. Class changes and EXP gains were awful in Echoes and you don't have to deal with that kind of nonsense in Three Houses.
I am talking about skills of your own units. There are more than ever before, probably to make up for the lack of weapon triangle; there are skills to improve accuracy, evade and attack when using any given weapon type, so that's that. Aside from that, almost all of the skills from Awakening and Fates are returning, including those that notably boost a stat for initiating an attack. All that stuff helps to overpower the regular enemies. The flipside is that special enemies like beasts and bosses are loaded with skills as well.
As for everyone being tanky, either you had extreme luck with stat growths or you bought lots of boosters and applied them.
Battles with a red question mark are entirely optional, so you've done some grinding. When you skip important days during the month, your units still gain skill EXP. You gain even more by choosing the seminar option each weekend, so if all you want to do during the month is about EXP, you can do a month in a few minutes. The most time-consuming activities in the monastery are all about support points.
We can't have a civil discussion until you bring down that shield of ignorance you've got up. No weapon triangle, Range Meta, overall tankier units, magic learned rather than being a weapon, combat arts, turn wheel, promotion increasing stats if below par, shields and rings, and so ons, all from Echoes.
I'm at Chapter 15. Which I think is fairly close to the end for my route.
HP + 5 isn't really that big of a deal with the amount of damage enemies do. It's nice in the early game, but All units definitely cannot tank hits. Unless I'm just drastically underleveled or something. My magic units are going to die around 100% of the time if left within range of a physical attacker. My bulkier units can usually survive one enemy attack, two if I'm lucky. Shields can help, but the better ones have a really high weight, which leaves you less likely to double attack and more likely to get double attacked. And that means sacrificing another item. By contrast in Fates, I would literally send Ryoma out into the battlefield completely unequipped (so he didn't get the kills) and let enemies wail on him.
By bows and magic that reach five range, the only such stuff I've encountered is the meteor spell (which is limited to one use) and the deadeye ability (with sniper class). Deadeye uses up a lot of durability and weakens your attack significantly. Also has a pretty low hit rate so you'll need to have an ability increasing hit percentage to use it effectively. (hit rate in general goes down the farther away you are). Good for softening up or finishing off units, but it's pretty much never going to one shot anything, so unless you send someone else in, you're going to wind up getting hit on the next turn. I still haven't gotten anyone to bow knight, so we'll see if that maybe makes bows too powerful.
As for gauntlets, they double attack, but their mt is really low. For example, silver gauntlets have an mt of 4 vs a silver lance having an mt of 13. Plus while the other weapons get a mt bonus for their + states, but the gauntlets don't. They also have imo the worst combat arts. In the early game they felt overpowered, but less and less as the game goes on.
You're also ignoring many features that the other games had that this one doesn't. You can't pair units which was absolutely broken in Awakening, and still a huge bonus in fates. There are less luck based abilities. Your crests kind of serve the same function, but they're not as overpowered as things like Ignis, Aether, or Dragon Fang. You can also only use rally on one ally at a time instead of boosting them all.
Aside from the fact that you can use divine pulse (which is a feature I like a lot), I'm finding the game to be overall more difficult than the 3DS entries. In Awakening and Fates, I found the early missions to be really tough, but once I settled in and figured out which abilities to exploit, the later missions became very easy. I'm finding the opposite here where I breezed through the early missions, but started having a lot of trouble (minor spoilers) after the time skip.
Lysithia is my frailest unit and she has 44 HP and 13 def (14 with current battalion) and is not even max level yet... What that means is an enemy has to have a whopping 59 attack to one shot her. Needless to say most enemys don't deal that much. And no, it wasn't lucky growths that got her that, promotion increases your base stats if they're below a certain threshold. If I wanted to I could give her a shield and a battalion with higher defense, but with +2 range from Thyrus she rarely gets attacked anyway. So if even my frailest unit can take a hit, imagine everyone else lul. Surely in your Fates example you mean Xander? Ryoma's defense is just average, on higher difficulities he'll die in 2-3 hits on his own. Eitherway, they're the head honchos, of course they'll be strong. Units like Elise and Azura however will die in 1 shot to just about anything, and overall most units die in 2 hits on their own as enemy damage caps between 40-50 while your units at max level have HP around 40 with 20-30 def.
Archer/Sniper have +1 Range, Bow Knight has +2 Range, so you can reach 4-5 when combined with Longbow and arts like Curved Shot and Hunter's Volley. There are 3 range spells like Thoron, and items that increase magic range. As for Gauntlets, using your example, a unit with base 25 str will have 50atk with training gauntlets, 39atk with Silver Lance+. That's the power of innate double attackin. As said already, they're not as good against armor, but otherwise will deal just as much if not more dmg, especially since their lightweight makes them the easiest to double with.
Tbh it's been ages since I played Awakening. That game is really broken and unbalanced as well, but I do remember actually feeling pressured and needing to think carefully about what I was doing. Then again it was my first Fire Emblem. Fates though clearly has more strategic depth. Even if you found it easier somehow (Birthright n Revelations sure, but Conquest?) that doesn't necessarily mean it's less involved. I mean for one you generally can't kill enemies without them attacking you, which is most relevant in a game where units die in 1-2 hits.