Of course I've heard of the OSI. I don't understand why I'm particularly bound to their definition of open source, given that both the phrase and the concept predate the OSI, likely by decades.
Why do you care? You have a particular vision of how your software should be able to be used. Why do you care if it's "open source" or not? At least with companies, I understand the reason for marketing purposes to be perceived as open source. I'm not sure I understand why an individual maintainer of a project is so desperate to be seen as being open source if it doesn't conform to their vision.
Why does anybody care about anything? It’s certainly not life or death for me; I guess I feel like it’s an unnecessary restriction of what “open source” could (and maybe even ought to) mean.
I’m not desperate to be perceived any way in the OSS community; I do plenty of work on projects that satisfy the OSI’s definition, and that will never change. But I also don’t see why the work I do, which I do for the public and not for corporations, which is open in the most literal sense of the word, can’t be rightfully called open source.
