Any vehicle with higher than average engine problem rate shows up in higher priced used engines. The people selling used auto parts know their business, the demand level, and charge accordingly. The Chrysler 2.7 liter V6 fiasco of the 2000s had those engines going for a fortune. My friend had one, perfect Mobil 1 maintenance and it still blew up at 80k and he got it done under the 100k warranty at the time. People that did not buy during that short lived longer warranty had to pay a TON for a new, rebuilt, or a still good junk yard engine. Cars that rarely, if ever, need replacement engines, those engines just sit forever and get prices cut. Something like a non turbo Accord engine can last forever if you don't take out the oil pan with a rock or suffer a quick lube oopsy. That lack of demand leads the parts dealers to sell them for whatever is worth shipping out an engine, about $500-800, and they could be shelving that part for years before geting that.
I'm only critical of the WRX because as a presitigious Japanese brand we really expect a lot. They seem to offer about industry average quality where we are used to exceptional japanese quality. When my golf breaks i will be like WOW you made it this long?? I'm gonna expect it.
I think there will be TONS of premature turbo engine vehicle problems alongside the CVT transmissions in the coming years. Things just not built to the same last forever standards. it is last for the warranty, have light weight parts for fuel economy, and by the time it blows up they hope to be selling electrics.
Everybody mods the WRX because its so easy to turn up a turbo car and its such a sporty chassis to work off of. Subaru, if they wanted, could have made the engine a lot beefier to stand up to the abuse. It is sold at a power level that is just fun enough to want a little more. It's the sports car equivalent of a free sample from a drug dealer. They are in the money making business and that is really just selling a bunch of crossovers to their [stereotypical subaru buyer] market and we should be glad they make any performance at all anymore.
Are the failures due to the mods, the drivers, or the design? Some combination of the three is my guess, mostly allocated to the drivers, then the mods, then the build quality last.