A lot of compression ends up being compress once, decompress one to a few times, so the faster end of the spectrum fits well. Additionally, compression has to fit into the existing system, and existing systems already have tight constraints, so it is an easier sell to say "hey, we can compress faster AND stronger" than what you have right now. For our larger services, we will tune the compression level more carefully, and end up at different places for different services, but still normally around the faster levels.

That said, we still see users of the stronger compression levels.