Great point. Most people can create an old-school website with a little effort using few or basic tools, but creating something that can host a community is/was much harder. phpbb was about the limit.
It's almost an inversion - instead of many community sites, there are many users together on a smaller number of community groups, which are generally built on social platforms such as reddit and Facebook which make it easy to create them. It's not necessarily a bad thing, except that the most invested people in the communities don't have ownership of the platform or the data, so the communities that matter to them are vulnerable to any arbitrary changes in what the platform owners choose to do.
It's almost an inversion - instead of many community sites, there are many users together on a smaller number of community groups, which are generally built on social platforms such as reddit and Facebook which make it easy to create them. It's not necessarily a bad thing, except that the most invested people in the communities don't have ownership of the platform or the data, so the communities that matter to them are vulnerable to any arbitrary changes in what the platform owners choose to do.