It's easy enough for an adult to follow setup instructions, but the ability ability for a kid to come home and set up their own minecraft server and bring in friends is cut down a lot when you go from "just about everyone has minecraft (java)" to "just about everyone has minecraft (bedrock)". Java is still there but it's not the thing everyone already has ready to go. That's especially true for vanilla but it also increases the amount of hurdles you have to go through to set up and use a modded java install.

And before they merged ownership, the gap between casual play and a custom java server went from "some setup time" in the earlier days to to "more setup time, also more than a hundred dollars purchasing copies of java version even though everyone in the group already owns minecraft". Surely you can see the lost opportunities there.