Honestly, GNU info was incredibly obnoxious and patronizing. you wanted to look up a few things, spend maybe 20 seconds reading and jump to examples and then go on with the next bit of that pipe'd workflow that was your actual concern. Software that used GNU info came with stub man pages that didn't give you that structured view (you know or might find that most man pages had the same structure, meaning one could process them mentally in a deterministic order) instead they gave you a short notice that said: 'this project uses GNU info for its documentation' and nothing more.
So you jump into info programname which isn't split into sections anymore, so you can't rely on looking at man 1 something or man 7 something and just pick - directly - what concerned you.
Instead you found yourself in a full training course on the said piece of software (which was potentially just a minor step of your workflow), which would have enough information to fully learn the whole design and all functionality of the program. usually they didn't include any examples, since you wouldn't need those if you already learned the whole design and all features, right?
It's an unknown number of articles you need to zap through, hoping you'll notice the information you're looking for. if you feel diligent, you'll try to read it all, but you don't actually know how many pages there will be. It burned you out to stay super attentive looking for information whilst getting lots and lots of information that just isn't that at all.
finally, you would like to not forget what you were going to do, so you cannot just dive in every info page either.
See the problem? They consistently ignored that the user looking at them likely was gonna do something. Like, that the users had a life happening at that moment.
Reading up on programs was important, and yes, you would fare well by doing that in your idle time. But that's what was usually nicely placed in /usr/share/doc for that purpose. And it was really nice to have a say in when you would do it.
Add to that the breaking with basic UNIX convention of how and when man pages were used by just supplying stubs on GNU/Linux, whereas you had working man pages on all other OS (plus really, really great manuals that were quite similar to what you'd find in info pages, just written by professional documentation writers with didactic background)
GNU info programs let users down instead of supporting them. They weren't approachable, harder to progress through, didn't give you a sense of how far away your needed information was, didn't reflect on their size in general. It was a tarpit, really annoying, and that's why it failed.
If they had instead supplied them as an addition to a shortened, concise man page and a good apropos like search (iirc there wasn't a way to search them all as easily(*)) they would have been a really cool addition. Ignoring the fact that there was a standard being used and just dropping in a new one without looking at the old thing was not very, "Free as in Freedom" and it was odd that especially in GNU land noone figured that. Back then people joked about the 'eat it' attitude in OpenBSD, but... guess what! OpenBSD had insanely good man pages, admittedly because they didn't want to be bothered by anyone. So they just laid out their rationales and usage really well. And it didn't need a new system. it just needed care.
(*) if there was, i'm sure someone will point out that and ignore the whole rest.
Anyway, I know it wasn't just me, I heard more than one friend go 'raaaaaaaaaaargh' when finding they needed to look at info docs instead of a man page.
manexisted since the dawn of time -- i.e., the mid 1970s. AFAIKhelpis quite a bit more recent that that.manvsinfo, to get to the question's "why," you have to apply opinion. Is verbosity actually better? Is it better to have a bunch of hyperlinked documentation sections or one big document? Etc. The OP obviously believesinfois better, but I likemanbetter. That's enough to prove we're in the land of opinion.infosince I never remember all the tricks of moving around in it. If you're going to have something that complex, why not use HTML and a browser? But that too is an opinion, I don't see how you can get a definite answer to this.