I think Active made sense for Lemmy initially, since it works a lot more like a phpBB forum board where each new comment bumps the thread to the top. I guess that made sense when Lemmy servers were relatively quiet.
Now that many new users are coming from Reddit and expecting it to behave accordingly, it makes more sense to switch to Hot as the default.
A bit like how putting "would" in a third conditional if-clause has become standard in US English ("We wouldn't have been late if we would have taken a taxi").
I know language evolves but it doesn't stop my left eye from twitching whenever I hear it.
Idiotic take of the day.