I would like to start this by saying that if the developer literally cannot give out enough free keys then it is a bad situation for him and the players. With that said however. I've been a developer on plenty of itch.io and steam products. You can usually get an indefinite amount of steam keys as long as you communicate with steam how many keys you need and for what purpose. So as long as nacho communicates with steam he had so many sales on itch.io. He should have been able to send keys out for each user. HOWEVER maybe steam decline him. I don't know the full situation. It just seems from what nacho has posted that he seemed to have put the minimum effort into communicating with steam.
No one is complaining they have to spend $3. They're complaining they have to re-buy the game in the first place. Which is perfectly understandable. Even more so when the developer had been quoted in the past saying he would give a free steam key.
On top of that he's removed being able to get the game on itch.io. ON TOP of that the game doesn't work on mac. ON TOP OF THAT the developer claimed free updates for itch.io users indefinitely. To then release a new version of the game on steam and discontinue the itch.io version.
There is a lot of reasons to be upset with the decisions the developer has made. The fact people keep going "wah wah its only $3 why are you'all crying" is them clearly not understanding why people are upset. It's not about the price. Its about the broken promises and other things i stated.
Hey man complaints is what makes a change. To just sit down and take it means any developer will have the same mindset. That's like saying "Never complain about league of legends, Apex legends, Counterstrike, etc..." because they're all free games. So any "complaints" are invalid because people are spending time complaining about a free game. It's just a strange mindset to have. The only validation is "bUt it'S onLy $3.". Whenever someone presents any valid reasoning to the issue it comes down to the money. Even though that's not the problem when complaining about free games are also valid.