At least on the communities i follow. Every so often I come across a thread where i recognize most of the users there even in the big communities with over 30k members and I haven’t even been on lemmy that long.
Same, I typically only comment if I have something new to add to the conversation. That being said, I probably comment more on lemmy then I used to on reddit simply because with a this smaller community there is more of a chance that what I want to share has not already been said.