This is so fucking annoying 

You buy a digital game and are basically trapped. Can't play your new game, can't play anything else online while your download keep running in background 

If internet becomes unstable when you are downloading fine, let me just turn off the online features for games such as Animal Crossing, Fire Emblem, Mario Odyssey and so on where the online playing is not mandatory 

You can play, but the download stops when the game starts

lmao

I do believe you. Guess people from some countries have good intenet connection to download things fast enough to not bother...

It's online some rankings for minigames, doesn't make any sense for me to stop a download 

I would understand Splatoon as it can somewhat mess with your connection. But in any case, there are options to play solo or local multiplayer, those features shouldn't stop your download 

It is like this for every console. I noticed on my Series X that the speed slows to 10 mbps (which may as well be stopped) just for having a game running, but as soon as I close it the speeds jump to 300-500 mbps. My PS4 Pro doesn't even let me use the full speed of my internet no matter what it is doing, and also goes even slower when playing online.

So this isn't isolated to Nintendo, and annoying no matter what platform it is on.

Interesting. My PS4 downloads just fine, I might have some speed drops when another game is running but I probably don't have good connection to really feel the hardware limiting the download speed 

It seems PS4 and Switch both throttle your download speeds.  For example, my X1 and XSX have always utilized the 500-600 mbps download speeds (as long as a game isn't running in the background, as I said before).

Now my PS4 Pro does get faster as my speeds increase, but it never comes close to what it should be getting.  Usually around 50-90 mbps (during non peak hours it sometimes breaks 100) when not playing online, and it does slow down considerably if I am playing a game with online features.

But the Switch almost always holds around 50 mbps, no matter what my speeds are (as long are faster than that of course).  The big difference is that, as you said, it will STOP a download when playing a game with ANY online features.

I suppose it is indeed worse than slowing the download speeds like the others do, but when I see my estimated download time go from 35 minutes to 23 hours...to me it feels the same.  I am still not getting to that new game the same day if I fire up an online game.

Slowing down downloads when game are runnig is understandable, downloaded data must be written in HDDs or SSDs or other mass storage, and as efficient and low priority it can be made, heavy writing activity could make other tasks, like the game played, run glitchy. Totally suspending downloads also for offline games, though, makes sense only if the game must access mass storage very often, and usually games try to avoid this, as without latest techs like PS5 fast SSD, it would make them run horribly.

I am pretty sure Nintendo does this because of evil forces in their corporate structure looking to destroy peoples lives.

It make sense since there are Nintendo games where if person is lagging then it affects everyone else. And also Nintendo have bad online in general. Doesn't bother a lot for me since I just stop playing while its downloading.