I’m fairly new - I joined last fall.
As a new player I would have absolutely looked at post history had the information been available to me. Being new, I would prefer to work with a GM that knows the ropes, the potential for ghosting notwithstanding. As I become more seasoned I would care about this less, and also be less flummoxed by a ghosting. From a functional standpoint, I think it makes sense to allow new players to pair themselves up with seasoned GMs if that’s what a new player wants, and this shouldn’t really hurt new GMs who have an established post history as a player. It might be nice for people to see post counts per game, although just the simple overall post count is a useful piece of information. It’s an indicator of investment. I would hope that a low post count on a new account wouldn’t stop people from letting them into a game... but I wouldn’t think that’s an issue. The culture here already seems quite welcoming and more data made available shouldn’t change that.
I also add my vote to having a PSA type post saying effectively "ghosting happens, don’t let it get to you, just join another game" in places a new person would see it. Forewarned is forearmed and all that, and good communication goes miles towards mitigating irritation or surprise. I like the word of mouth idea, but I’ve seen sock puppets vouch for sock puppets on other specialty social media before, and it takes a new person awhile to learn who can provide a reliable testimonial. Once again, overall post count information can help people corroborate.