But where does "using gear 'incorrectly'" end and "using gear in a way I don't like, or under conditions I don't like, or to create sounds/styles I don't like" begin? How big a problem is someone with their Altoids tin shaker-thru-DigiTech Death Metal harsh noise project, really, even when they branch out to buying boutique equipment?

It makes no sense to labor that particular point as it's an exceptionally rare case where some filthy-rich fruitcake hoards Trent Reznor/Richard D. James quantities of truly exquisite gear and can't/won't do anything with it. In the majority of cases, people are spending their own money on readily-available equipment. Equipment they sell at a discounted price to YOU if/when they realize they're not making it as Prurient 2.0 or whatever. This is truly a non-issue.

The one exception, perhaps, being common, "overnight cult successes", most of which are purely hype-based gimmicks to begin with (Sitar Swami, anyone?). And we have only the Internet Buzz (Bull) Machine to thank for that.