I think it depends on 1) how “in depth” you want the commentary and 2) how public. There are a lot of writers’ forums online, for various styles and genres, where people do a version of an online writing group to critique and encourage each other, but those are usually only for forum members. Doing something like that here, on Medium, which is open for comments by any ole hooch dog could get…oppressive, rather than supportive.
I like the “Sunday Six” concept, where writers post six sentences of a WIP every Sunday. It’s usually done as a “sneak peek” but it could be spun as a way to garner feedback.
This was one huge advantage of LJ; you could post whole chapters of works in progress but lock it down to just those people you wanted to read it. I was just talking to JenS about how awesome it used to be to post fanfic on LJ, because we often got some really thoughtful feedback, and we miss that.
I keep toying with the idea of posting chapters of WoHH as they come out of edits to Wattpad or AO3, for feedback from readers before collecting it all together to publish. Dunno.
A lot really depends on the community aspect, I guess. THere are a lot of great and mutually supportive writers here on Medium, but being wide open to the public, I’m wary of opening up my “writing process” too much. But that’s just me.