There's a disturbing pattern of small devs using Itch as a springboard, and then as soon as the game gets traction they sell out and leave all of the Itch users behind with crappy or zero support.
Don't get me wrong, I don't mind the exclusion of leaderboards on Itch, since leaderboards need to be centralized. But multiplayer doesn't need to be centralized. And it sounds very much like multiplayer's only coming to Steam, with always-online DRM, even though netplay could easily be allowed on private LAN or VPN.
So us who bought the game DRM-free on Itch are being told to buy again at full price if we want the new features, and also those features are going to have horrible DRM tacked on.
There are a lot of simple kids out there who downplay stuff like this by saying it's "just $3", but it's more about the principle than the amount. Devs who get used to doing scummy things in their $3 games will go on to do scummy things in their $30 games.
Any dev who pulls a fast one and takes $1 of your money would take $60 if he could; he just doesn't have the budget to yet.