I've seen a few here and there but the only ones that really come to mind as outright -being- there in public were some people roleplaying as the Sultana and some of the Scions. I easily ignored them though I know it was hard for some others when one of them (who later was mentioned as being new) tried to force it into the open. It was cringe-inducing in a way.
I think part of the problem is that a lot of blog-related roleplay (at least those I have been exposed to on Livejournal, Tumblr, etc.) have a preference of taking established NPC canon characters and rolling with them. So I think some of these roleplayers come into FFXIV and want to engage into their usual. In these, OCs tend to be looked at with side glances. These RPs though tend to be more closed off or not forcing these types of headcanons into the public. Ask-blogs seem to be a bit of an offshoot from this which at times can be quite entertaining.
I think part of the problem is that a lot of blog-related roleplay (at least those I have been exposed to on Livejournal, Tumblr, etc.) have a preference of taking established NPC canon characters and rolling with them. So I think some of these roleplayers come into FFXIV and want to engage into their usual. In these, OCs tend to be looked at with side glances. These RPs though tend to be more closed off or not forcing these types of headcanons into the public. Ask-blogs seem to be a bit of an offshoot from this which at times can be quite entertaining.