I agree with you completely. That said, part of the thing this community will struggle with is that there are "primary" communities for most of the things people make (woodworking, leather making, luther, 3D printing, quilting, etc). It's kind of nice to have a community that looks across other communities, but what should be posted here? Is this a best-of things people made or is this a repost repository? I'm not sure what a good answer is.
I mostly crosspost here when I finish knitting a nice pair of socks. Occasionally hint at other crafters that they should do the same with their finished projects, to limited success. Of course there are plenty crafts that don't have a community yet, too, so it's nice to have an enthusiastic catch-all community like this for when it's needed.
That's fair. I have reasonably mainstream hobbies when it comes to making things, so most of them have a dedicated community. Not all those communities are very active though. I try to nurture some of them with content and am personally not a big fan of posting the same content in multiple spots. Maybe I should give up on some of the smaller communities for now.
Here's a list. Note that there's a decent amount of fragmentation due to multiple communities filling the same niche in different instances, as well as sub communities (see: functional printing and fix my print vs 3D Printing and birding and travel photography vs photography)
Obviously very much up to you but I do think crossposting has its place! Actual crossposting, not duplicate posts, important distinction there. Doesn't show up twice in people's feeds, but lets you reach both the small niche audience in the original hobby community and then also the potentially wider audience in a community like this! And of course, lets people in the bigger community know the smaller one exists.