Hopefully, I might still try and play it safe and have the SFW mode on by default, but players can easily change to NSFW mode by going into the Settings Menu.
Viewing post in Next Public Demo will release Uncensored!! comments
From what I remember, those accounts did not lose the ability to sell their game on itch. But rather itch did not want to act as merchant for them. While itch did not state clearly any specific reasons, I suspect a combination of different factors, including international tax issues and a cost/risk evaluation (all of which are higher for adult games). The accounts would still be able to sell with direct payments, but that is not possible for some accounts, due to payment processor restrictions. But they would still be able to have a game page and advertise their steam, patreon, subscribestar and whatnot. I would hardly call that a ban on adult games, as some called it back then.
Having sfw on by default will not gonna change anything about this.
But having a sfw mode will definitly open up some interesting possibilities, including making it easier for some streamers to play your game.
You might even consider a "sfw" release that can be (officially) patched to be nsfw. Some anime style games do that. Possibly to have a non restricted rating on Steam, so they can be browsed unrestriced and even sold in markets like Germany.