Yes it says you can only have one project, but that is completely based on accounts. You could have other members start other projects or simply make a new account, and then invite unlimited people to it. Even though it’s obviously not the best for creating projects with a team, it still fits as an example that is free, and has collaborative editing.
And also, why does it matter if not many businesses could afford it? I don’t remember this being an application solely for businesses. For example, I am trying to use Bootstrap Studio to develop frontend with some of my friends for a company they have started. It would cost no extra to do this, and would be an incredibly great feature.
Last thing, I don’t think it would require the Bootstrap team to rewrite the entire program for collaborative editing. Connecting through IP (although not the best or most secure option) would be a completely free choice to enable collaborative editing, without the developers having to pay for hosting. They would just have to send data through the IP’s and then replicate that data to the main save file. You can see something like this done through Visual Studio Code.
I don’t think Bootstrap Studio is a bad program. I actually really enjoy it over anything else I’ve used. All I’m saying is many other programs that are free can do things like this, and this would be an incredible feature to have, seeing as how other people suggested this before.