That's what I've always thought of Open Source... until I found out Open Source projects that are not in the spirit of Open Source. Signal is a big example of that. It's hostile to forks, didn't publish its source code for a year and doesn't have a good documentation.
Same thing for Nvidia, big browser projects like Chromium, and Android. Many Chromium forks died because they couldn't keep up with upstream, except for ungoogled-chromium.
This is untrue. Both "free" and "open" licenses do the same thing in this context: they are legal documents that tell you what different parties are able to do with the code, but none of the licenses mandate how you run your project: whether you must accept contributions from others, whether you provide a bug tracker, or anything else like that.
Hell, you could have a GPL project that is developed entirely behind closed doors, as long as you always give users a copy of the source code when you release a new version.
Same thing for Nvidia, big browser projects like Chromium, and Android. Many Chromium forks died because they couldn't keep up with upstream, except for ungoogled-chromium.