I would hope it actually is more known among developers. Even big titles like Tekken 7 used it. Insistence on crossplay with consoles causes a stumbling block, but still, that's not most games.

https://partner.steamgames.com/doc/sdk/api/example provides a good example, too. Steam has all sorts of extra functionality to justify their 30% cut on sales, they're not just taking it while doing nothing.

It is well known. But also not all developers want to/ can afford the risk to tie all their networking services to Steam.