This is a big one. I switched from GnuCash to QBO for a non-profit because of that.
One would think it can't be that hard to put together a webapp to freaking sum up some numbers, but nobody seem to want to do it in open source.
It could be because it's indeed so easy that it's boring, or could be that anyone with the necessary knowledge of accounting standards makes way more money doing other stuff than coding for free.
Users can slowly adapt, but most businesses larger than a sole proprietorship need multiuser capability.