To be honest, I never agreed with those who demanded a steam key. But now, I think I'm on their side, allow me to explain:
Before, for me, there was no difference between steam and itch.io, even Itch.io version was better, because I own it, but now, the itch.io version has a huge downside compared to steam's version, which makes me feel, let's say, a bit betrayed.
I know that 3 USD isn't much. For USA standards, many people is not from USA and 3 USD are still low, but way more than for someone from USA or EU.
Anyways, at this moment, I think Mike should either provide a steam key to everyone (who purchased on itch.io) or add the multiplayer to itch.io version, because it's not fair for us to have to pay again for something he maybe didn't even think about before.
I'm sad to say it, but if he doesn't solve anything, it would be a "huge company maneuver" but on an indie developer, isn't Indie community against those practices?
Thank you for reading. And for those wondering, if he doesn't provide anything, I'll do nothing but remove my support for future projects nor purchase steam version, that's my course of action.