I'm actually going to start using my old 720p 26" Sony from 2007(?) Soon in a spare room.
I only really use that room for VR and light background TV when working, so I'm it's good enough.
I also have my old svga Compaq/HP monitor from 2004 which I use for retro stuff, but I need to find another old NEC one I should have somewhere as I'm hoping it can handle 15khz signals.
Plus, it has a feature which I boot up the PS3 and the TV boots up itself, that's pretty neat
AFAIK That's just a feature of HDMI-CEC, so other brands with the feature should also work, although the Xbone also does something but IIRC thats with IR.
Meanwhile, newer TVs seem to be less reliable and its users are somewhat happy buying one yearly, like it's an iPhone or something. I don't get it, a TV is supposed to last for years.
I can't comment on the reliability rate, only anecdotally it doesn't seem that bad with most faults being OOTB and only the occasional within the first year return/repair.
However, I wouldn't be surprised if allot of people are upgrading sooner because of two reasons:
1) TVs are ridiculously cheap now, I was looking at potentially getting a 32" but then realised a 43" wasn't that much more.
2) Functionality pushing people to upgrade, especially smart functionality
Personally I do think the latter is stupid if true, but I do know people who
insist demand an AIO smart device. My personal advice to anyone buying a smart TV is 'buy a decent TV first, smart device second, since the latter can always be added later', but some people treat additional cables like an arachnophobic treats a spider, even if it's hidden.
That said, when I accidentally broke my previous TV, I did take the opportunity to upgrade to a set which has features like higher refresh rates and Dolby Vision support, still use my 'old' Shield TV though.