A recording engineer's job is to do essentially this, not just with guitar signal chains but also with microphones and plugins for vocals or any instrument. He's hired by people who've (hopefully) gotten the composition and the musicianship sorted out, and they need somebody whose expertise lies is getting the sound the client wants to hear in the mix at the end of the day. This is at least as broad and challenging as performance and composition.
As a hobbyist songwriter who's lucky to gross $20 and a PBR on a gig, I won't be too harsh in criticizing another hobbyist who's enjoying the time he spends with his gear. An engineer with no client seems silly, but most amateur musicians have no audience.
There's a stereotype of guys who just buy stuff and post pictures on Reddit, but I don't know how many of them are really doing nothing with the gear.