Dude, my setup is not worrying me about gaming, I just don't see passion in games anymore, I'm used to games that are from early-mid 2000s, I tried gta v imo it sucks, I tried fortnite imo it sucks, I tried far cry 3 and 4 it sucks, tried assasin's creed after ezio and altair stories, imo they suck.. it's not about pc or performance it's about other stuff which is hard to explain in short words..
"Your friend would've bought the R9 3900X in this example, and paid well over double the price of an R5 3600 for relatively minimal gaming performance gains." yes, maybe if we're talking about today, but back then 5 years ago amd was literally not an option, intel could put up prices high up as much as they want even more than they do now+ consider the fact that prices are not the same in every country..(in croatia's case it's without a doubt more expensive)
I know that i7 would be a better option back then but you need to understand that I paid 800 euros for the pc, if I put i7 it would be 900, if i added something else or did some minor upgrade would be easy 1000 and the fact is that back then avg salary was 500 euros.. and I paid i5 over 200 euros
To give you an example of "average" pc back then, in 2008 or so I bought a pc with dual core amd 2.6ghz(idk exactly which model) cpu, 9600GT 512mb and 2gb of ram(later upgraded to 4gb), that setup could run apb,crysis, dayz and pretty much nearly every game for next 6 or so years, my friends(most of them or a lot of them) couldn't even start those games or if they could they would either play on 20fps or remove every single graphic object to play on 40.. that was the average pc back then and it was from 2008-2014, in 2014 I bought new setup