That's not exactly a FOSS problem, though. Nothing stops an open source project from offering the same collaborative features as proprietary solutions.
It just seems that people who work on FOSS value privacy, ownership and freedom more than braindead ease of use and monetization.
That seems to be an unfair dismissal of these products. The vast majority of everything built with these tools will be public facing. Marketing designs, UI design, etc.
Design is a very collaborative process, especially with remote work which has made having everyone see and edit the same thing at once critical. It's not "braindead" to work in a team, its a requirement. I really want to see FOSS succeed but its hard to see how the open source benefits translate over to this kind of software where you no longer run the software locally and consistency is needed so others have the same version of the tool as you.
It just seems that people who work on FOSS value privacy, ownership and freedom more than braindead ease of use and monetization.