I'd buy albums off Bandcamp for artists I already know, but I wouldn't use it for discovery. Do they even have discovery features? (I honestly don't know)

Steam's recommendations (and more importantly, sales) are how I discover new games. And there's a lot of titles (both games and music) I'd happily pay $2 or $5 for, but not $20 or $50. There's a lot MORE titles I'd be happy to try for a monthly all inclusive subscription.

For music, I wish Spotify would add a "Like this track? As a Premium subscriber, you can buy the whole album for only $5!" function. That's way less than a full price album but still way more money than the artist would get from streaming.

Disagree. Bandcamp doesn't require a bloated desktop app that needs to install a bunch of updates every time you open it. Songs you download are yours to play and distribute as you please. They don't require an active Internet connection to check your license and track your listening habits.

Besides that, Steam is the go-to place to publish games. The only reason you wouldn't distribute on Steam is if you are a Nintendo or Epic-level megacorp that has its own store and exclusivity rules. On Bandcamp, the decision to upload an album comes down to whether the record label allows it. So a lot of times, artists will post early works to BC and drop it as soon as they sign with a label.

The Epic Games Store of music, surely.

That was probably true before Epic bought them. Less so now.