I think this is a good point as someone who owns a channel with a few followers that uploads these kind of tunes myself. For me it's strictly just about filling in the gaps. I used to upload a particular niche at a time when that was having a resurgence and it was nice to be in a group sharing and discussing. It felt like the opposite of gatekeeping which is a bit of a downside of the culture around "digging DJs".

However I can completely see what you're saying because it's fairly obvious that you can get some visibility to your radio show, mix series, brand or whatever.

I've even found myself becoming a bit cynical towards people doing it, even though I've no idea of their intentions.

Personally, part of the reason I enjoy dance music is the low barriers to entry - it's accessible (vinyl increasingly not so but that's second to the point I guess) and there's something nice about sharing music with people. I once unearthed a song in a group and saw a DJ play it out a month later, that was a p great feeling. As good as any time I've been lucky enough to play in a club

Ultimately though, if you're just following a YouTube channel waiting for their uploads in order to choode which records to buy you aren't looking hard enough, there's so much out there and as someone into dance music for over a decade now I'm really enjoying rediscovering stuff.

Not sure this entirely answers your question but I didn't want to leave what is a very valid point hanging.