Communities generally spawn on whatever general purpose instance, and I’m fine with it because the only other option is usually nothing at all. Maintaining an instance takes hard work and money.
Sometimes there is enough will to spawn a specific instance. For example, rimmers have their own mbin instance. That’s the exception, though.
The only encouraging thing I can say here is Be the change you wish to see. If you want an instance to exist, run it yourself!
I’d be fine with world. If you aren’t, maybe sopuli.
I don’t think most instances run alternative frontends so if you want them to provide the old reddit thing, your list of options might be short.