He's not asking them to be penalized, just to let people choose what their speed is. I get the same problem on mastodon: there are users there whose posts I really appreciate and find interesting but I had to unsubscribe from because their posting frequency flooded out everything else. I just check up on their feed separately every once in awhile instead

I'm not asking for some strict formula, more some ability for people to describe what kinds of blogs they're after in more detail in a way that's flexible, but not overly fiddly to use.

I'd possibly put a shared blog under a similar category as the ones with weekly roundups. Which is exactly why I threw out that example - I don't want hard-and-fast Google-style rules, because I would expect that to work out about as well as hard-and-fast Google-style rules ever does.