Oh, it's more than that. 2012 is roughly the point when computers became fast enough for most people. A 2012 MacBook Pro with a SSD and 16GB RAM (or, really, even 8GB RAM) is perfectly capable of running current macOS 14 and handling day to day use for most people.
It's not obsolete at all.
Sure, a 2023 MBP is a little faster. But it's not really all that noticeably faster doing most things that most people do day to day. I mean, I'm typing this on a 2015 MBP running macOS 14, and it's absolutely fine, it's my daily driver right now, I do almost everything on it, and I've got a 2012 MBP running 10.14 sitting right beside it that I still use pretty regularly when I need to run 32-bit apps that's almost as fast. I've touched brand new Macs, set them up for clients, and they're not that much faster than this 2015.
The power and speed increases over the last decade... haven't been that much. Compare a 2012 to a 2002, and you'll see a huge jump in capabilities, 2012 to 2022 looks nothing like that. And 1992 to 2002 - wow, that's a PowerBook 140 (I have one of those) to a TiBook G4 (got a few of those too) - the change is unreal.
Technology advances have slowed down. macOS releases have become change for the sake of change, not anything that really improves our lives, and in many cases making things worse. After all, did your life somehow get better when 32-bit app support was dropped? When PowerPC apps stopped working? When the UI went from "lickable" to flat and ugly? When scroll arrows disappeared? (Yeah, I still want my scroll arrows back.) When System Preferences became System Settings and everything moved around yet again?
The reality is that computers just aren't getting better any more. Every tiny incremental speed increase comes with software changes that make our lives just a little bit worse.