Also Write.as is yet another centralized and proprietary solution...
There is a lot more, but those would be most notable solutions for self hosted blogging (and mostly supported by Github or Gitlab pages which are free, all you need is domain)
At present, those who write about opensource and security are at least going to be technically inclined. So the only excuse they have for still using Medium is exposure
I can understand wanting to reach a wider audience, but from a vendor lockin standpoint, the difference in priorities can't be reconciled by staying with Medium