Why do I need to research ? They are tried and tested in real world application ?
Aging Capacitors ? The efficacy and efficiency of electrical components decreases with age and use ? The concept is completely foreign to me.
Sure it's quite certain "maker" actually tests PSUs to determine their endurance for deciding warranty length.
Just put PSU under load in controlled increased ambient temperatures and you accelerate aging.
Basically life time of electrolytic capacitors halves for every 10C increase in ambient.
So rise ambient 30C and they age at 8 times the normal speed, 40C for 16x aging, 50C for 32x aging...
And cheap PSUs use cheaper caps with lower endurance and lower amount of work load they can endure staying inside specified endurance.
In worst case they're even specified only for 85C ambient instead of standard good level of 105C.
Or cheap factory could use capacitors with fake specs made by scammer company.
Basic semiconductors like diodes and transistors again are very much on-off parts in their durability when otherwise used with in spec:
They work fine until quite high temperatures, at which point they start dying fast/instantly.
Hence if those are properly size with proper cooling when needed and there are no weak solder joints, it's mostly capacitors which decide life span of device.
It was failing capacitors which got replaced when people took their old CRT TVs to repairman in the past for all those problems of image "shaking"/being misaligned/missized when powered.