I think even the parts availability argument starts to fall apart with scales of economy in manufacturing. I can walk into Best Buy today and walk out with a brand new 65" QLED 4k TV for $299 + tax. How much money is someone willing to spend to fix a $300 item? Even if the parts are free, you're better off replacing it if it's going to take more than an hour to fix. Keep in mind the overhead of finding a repair shop, scheduling a drop off, dropping off the TV, waiting for the TV to be repaired, picking up the TV again and remounting it. You can cut more than half of those steps out by buying a new one and it'll be available within the hour. At the rate of progression, it may even be an upgrade!
Most of the time the failed part is either the power supply board or a backlight and they’re usually available as aftermarket if you can’t be bothered to isolate the failed micro component or LED “bulb” and solder one in from a donor. Or a flex cable that just needs reseating.
PS is probably harder nowadays since it might be more integrated but not 10+ years ago.
It's really amazing how I quoted a repair shop owner saying the problem is parts availability and got two responses basically saying "nuh uh."
I have a more recent personal experience. My parents refrigerator went out. The repair man came out and diagnosed it as a bad inverter board and he'd get the part and come back in a few days. Great! The next day he calls my dad and tells him the part isn't available from the manufacturer so he can't actually fix it.
So I helped my dad go on an internet search and we eventually found an aftermarket (counterfeit?) board and installed it ourselves. My parents were thrilled they didn't have to buy a new refrigerator, but the repair guy got paid for the diagnosis but didn't make any money for the repair. I don't know if that's a long term sustainable business.
This is why when I replaced my appliances I chose GE/Hotpoint. GE does their own in house parts and service, and in particular Hotpoint is easy to fix with a screwdriver.