Probably a very polarizing question.
On the one hand, having most of the users and communities on LW causes technical issues (see this post), and also gives the LW staff too much power over Lemmy as a whole.
On the other hand, with 18k MAU on LW out of 47k (https://fedidb.org/software/lemmy/), every community listed there has a much higher chance of visibility compared to an alternative hosted on another instance
Not sure, might be, I’m too lazy to setup another LW account to find out ha ha.
Might also just be that it’s their way of avoiding political content from lemmygrad, hexbear and lemmy.ml