I agree with your main point, but I can't resist pointing out some huge exceptions since there are some mammoth fully open projects like:
- The linux kernel
- Languages (Rust, Python)
- Airflow
- Libre Office
Either way, I think the important thing is knowing why you want something to be open source (do you want to self host? Own your data? Fix bugs? Do you have doubts that the developing company will last long?) Some of those will work great with an open core model, others won't. I think if Linux was "open core" it wouldn't get used at all, that's a lot less true of something like libre office.
All completely valid counter-arguments. In my defence my perspective is very narrow towards only self-hostable open source tools. Like the types you might wanna self-host in a company anywhere between 10 and 200 employees. I don't have any knowledge of, say, open source libraries and how they operate, and the same applies to all of the exceptions you've listed except LibreOffice.
To be even more specific: I was responsible for maintaining three OpenProject installations in three completely different places. One is a small non-profit that couldn't realistically afford anything else, one is a cheap and very poorly-managed for-profit company, and one is a much larger non-profit that ultimately ended up paying for some "better" proprietary solution. The only things I could think of that those three places have in common are: I worked there, and OpenProject was used to some extent, even if only briefly. And it was never because of me! Other people have made that decision, but it was my responsibility to maintain it.
- The linux kernel
- Languages (Rust, Python)
- Airflow
- Libre Office
Either way, I think the important thing is knowing why you want something to be open source (do you want to self host? Own your data? Fix bugs? Do you have doubts that the developing company will last long?) Some of those will work great with an open core model, others won't. I think if Linux was "open core" it wouldn't get used at all, that's a lot less true of something like libre office.