I'll probably still stick to OLED though unless there's a new technology that can give me the same blacks and brights; can't keep up with all of the new marketing terms these days so not sure if there is something that can compete but last longer.

It comes down to a few people don't knowing a lot about it - and I'm not blaming anyone for that, we all have our interests and most people have more than enough to do already to worry about what goes on inside their stuff.

Also, electronics are, to a lot of people in a lot of places, so cheap that they would rather just curse a little and buy a new thing, instead of bothering with taking the thing to a shop. And of course a few hours of skilled labour in a big city in the west might also be almost as expensive as making a whole new TV in a factory in Asia plus shipping, so it might not even make economic sense.

The 2nd most common failure mode gotta be the mlcc (multi layer ceramic capacitor) cracks/shorts.

Measuring voltages, peak to peak, is a bit more work.

You can look for physical signs of degredation (bulgy, leaky, discolored), but to really test a capacitor for capacititance, you need to take it out of the circuit, at which point, you may as well put a new, high quality capacitor in.

The OEM capacitors may likely have a just right voltage rating, a new one with a higher voltage rating (and same capacitance, compatible type) may last longer in cirucit as well.