It's a combination of whimsical requirements from PMs and designers, plus FOMO and resume-driven development among developers. None of which have anything to do with actual end-user needs.

Companies overhire devs after raising money so it looks like they're doing a lot of interesting stuff. PMs and managers need to find stuff for these devs to do, hence they come up with overcomplicating their existing tech, redesigns, etc.

And on top of that, most users want it to work the same it worked yesterday. Nothing drives me up the wall more than neverending stream of updates for anything and everything, be it PC, mobile, web, even cars. I understand it's great for job security and/or resume-filling, I just wish those developers would consider the difficulty of,for example, trying to explain to 60 years old nurse why the thing that worked yesterday doesn't work anymore or why it suddenly behaves differently.