Last time I built an entire computer was around 2002; some AMD Athlon-based rig with a piece of garbage videocard from Internet I-Shop (before they packed up and vanished). I'd tried building a simple Pentium-based machine before that, accidentally connected the PSU cable to the MB backwards (they weren't keyed back then), and fried it all. That pre-built was okay after I upgraded the video card, though. I held on to various parts through multiple upgrades, and eventually, I had a totally different PC than the one I'd originally purchased.
After that, I just built 'em all.
People like to talk about reliability of cherry-picked components, but it's always been a crap shoot for me. Seasonic, Seagate, Antec, Asus... everybody makes garbage now and then. My main benefit is knowing exactly what parts are in the machine & knowing exactly what they're capable of.