.NET is the most open, non-trivial ecosystem I have ever participated in. I experienced 2 different problems with .NET (back in 2.x/3.x days), and was able to have interaction with the actual MS developers on their Github issue page without any sort of bullshit overhead process. Within days, I saw traction on my comments and within months I saw PRs that ultimately resolved the issue I presented. The following year, I…
I think the OP is talking about "open" in large part in terms of open source licenses, and intellectual property. They complain about "subvert[ing] an active open source project by ramming in a proprietary extension to continue to lockdown .NET" and "Over time, the .NET platform is becoming closed, to ensure it is only useful if you are a customer."
You are talking about "open" in terms of access to developers at Microsoft, who you can commicate with, and who then respond by getting fixes to your problems in.
These are actually pretty different things. You and OP can both be entirely right. .Net can be a platform where Microsoft is working to make sure that the platform is only useful if you are paying customer, and where you have access to communicate with developers who take your concerns seriously.
> Are we upset that we have to pay money for the privilege of using other peoples' intellectual property
Well, I mean... you know what open source is, right? Yes, it means you don't have to pay money for the privilege of using other people's intellectual property. That's literally what open source is.
That's fine if you don't care whether or not .Net is open source. That's fine if you think it's silly to be upset that something isn't open source when you think it should be.
But... .Net claims to be open source, right? So, yes, it is reasonable to expect you can use it without "paying for the privilege of using other peoples' intellectual property". That's literally what open source is?