That's not the definition of "open source", that's the definition of "free software". As you can see by this very article, "open" and "free" are not the same.
The only difference is their argument. Free software uses ethical arguments, open source denies ethics altogether and uses consequentialist arguments related to business value and technical superiority (which are becoming increasingly criticized).
Yes. Because of the ethical standpoint, free software inherently opposes DRM, Tivoization, "trusted computing" and software patents, whereas open source in general has no intrinsic view on them.
It's far from irrelevant. Free software advocates are clear: proprietary software is unacceptable, in any form, for any reason.
It has nothing to do with being ungrateful. We express our appreciation when software is liberated, or when developers/companies are working toward it. But it does not change the fundamental philosophy.
Irrelevant to you perhaps. But please don't tell people to shut up. What you say can also be regarded as whining btw - you mean good, I think, but this just won't help one bit. Better to participate constructively than to express this type of annoyance.
But that's the enterprise license, not the community license.
When they say "In fact, even our proprietary version of GitLab, GitLab Enterprise Edition, has a publicly viewable source code", I don't think they're implying it's open source.
> Open source software is software that can be freely used, changed, and shared (in modified or unmodified form) by anyone.