Actually, you can beat FFIX in less than 11 hours (in the NTSC version) plus you'll get Steiner's strongest weapon, the Excalibur II, if you reach Lich in Memoria in under 12 hours. On the PAL version that's impossible, due to the lower framerate (50 FPS), the fastest speed run on the PAL version is 13 hours and a half.

I agree with the overall concept of your post. Speed running is a fine and dandy option if you wish to pursue it, but don't got claiming that it's a detriment to the game if you forced your way through it as fast as you could as that's not the actual experience the average gamer gets from the game.
Some of the times that people post here from previous FFs baffled me, especially the one claiming to 100% FFX-2 in 28 hours without doing Via Infinito, which is impossible as Via Infinito adds % to your game, as you have to beat Trema to get Trema Episode Completed. And getting 100% on FFX in 70-ish hours, even if it is on the US version, which even without having the Dark Aeons and Penance, still has the Monster Arena and Nemesis, thus farming all the required stat spheres to get to 200+ stats plus getting the Celestial Weapons powered up (even the fastest quest, Tidus's one, takes some time to complete) to be even able to scratch Nemesis and to survive his most basic attacks (up to 20K damage per character) just seems rather impossible. 

OT - I haven't got FFXIII-2, but 46 hours do seem too fast from what I've read here in VGC and other sites from people playing it, but with a guide it becomes more feasible, though I personally don't see why one would rush through a game like that. 

Played 4 hours of this game and stoped, absolutely hated it

I still have XIII-2 unopened on a shelf until I tire of collecting and dishing out knee arrows
But then MEffect coming on the 9th. looks like it's gonna be a while until I get around to this, let alone platinum it

OP:Gratz BTW

No doubt you did everything, you followed the guide begin to end. Maybe that's also why after 5 hours it "fell down a bit". Instead of exploring you went straight picking up the items.  Whats the fun playing such a beautiful game (well, any game actually) starting with the trophies in mind. Especially knowing that FF XIII-2 has no missable trophies. 

In any case I'd say as well that without following a guide step by step (and hopefully playing only on Normal) there is no way one can plat the game in such a short time. Without any guide at all it would take even 100 hours minimum. I'd just like to see someone claiming that she or he can solve all Academia quizzes without making a single mistake in 10 questions. I admit I did use a guide for that piece. And for the bestiary fragment as well. 

Come on guys stop picking on Iveyboi.

Hey man! :P there's a 110% available in the game.  You only have to get to floor 20 to get the crimson spheres.

FFX I guess I didn't 100% it :P.

I remember there being a Screenshot of someone Platinuming 13-2 in 40. That 6 hour differnce is maybe skipping cutscenes, or just faster, idk.

No there isn't for a single completion. 

For a single completion 100%, you need to go through Via Infinito. The 110% only happens in NG+ and by that time, you might as well be playing it on cheat mode, since you have all the items, all garment grids, all dresspheres, key items for the Break Limits for the Special dresspheres and all mastered abilities from each individual character&dressphere. So unless you want to talk multiple playthroughs to get those 110%, you can't possibly count those 28 hours enough to 100% FFX-2.