This isn't a qu-- actually you heard that already (˃ . ˂˶)

I can definitely attest to the culture, which is fresh air compared to a lot of networks (e.g. that Draw a Duck post is probably far beyond a lot of platforms' capabilities/proclivities)

I think some of it boils down to:

• The Lemmy Algorithm. This is a big flaw with Reddit -- people have the attention span for the first ten comments, and then subcomment upvotes halve (with decent std. dev -- we aren't Zipf's Law devotees there) until invisibility. I don't think my Reddit comments are even seen, let alone replied to. But here, new comments have a chance.
• The sense of "mineness". As another here said, there's responsibility to raise your communities right, and another to interact (hence, variably lower hostility). I don't post much but I respond a lot to the people who comment in them, because I feel that I have to contribute to keep this sanctum humanly alive.
• At risk of sounding self-absorbed/elitist, the entry level. People are here because they were dissatisfied with the state of other sites, then made a jump; this is a sieve that to an extent increases the standard of sorting by new. (This has limitations of course, and it isn't necessarily advocating for Lemmy to never be mainstream.)

Just my conjectures ¯\_(ツ)_/¯