Gatekeeping isn't boolean, it falls on a spectrum. If your rationale about preventing un 'authorized' use is in fact true, the process must be effectively keeping some notional gate some kind of closed even if it's only from people you (or maybe even the original artist) consider to be acting 'unscrupulously.'

If musicians' priorities were for the world to share in their musical indulgence not just in listening but also in like-minded creation, they would release as much of their mixing tools/backgrounds/stems/etc as possible. Since the capitalist framework is a foregone conclusion, they need to keep some secrets in their sauce to produce scarcity to justify a price for their labor so they can eat... Because the farmers and butchers all keep gates of their own kind, too :)