My nextdoor neighbor is a shoe salesman (in the US). He traditionally dealt with a region of retailers on behalf of his employer, a multi-brand company like VF, Clarks, Born, etc. In his previous role, he was asked to try to figure out how to add Amazon as a B2C channel. He did, and it essentially became his full time job. A couple of years ago he was laid off, and when his new employer (differently shoe company) learned he knew how to "use Amazon" he was immediately reassigned from field sales to full time online. According to him, there are so many quirky and esoteric things about selling through Amazon it's nearly impossible to figure out how to get started, much less understand nuances of pricing, taxes, shipping and returns, and -- as you said -- Amazon support is conflicting and inconsistent at best.

Nowadays, I'm fine buying consumables from Amazon if I need them asap, but for any name brand stuff I specifically want, I prefer purchasing elsewhere. If reviews were trustworthy, it'd be one thing, but with Amazon having turned into AliExpress, it's impossible to know whether any of the Chinese brands are actually trustworthy and of high quality.