well, you have to admit its a little confusing. its so free, that by accepting it, I can constraint your future behavior (making it less free really), so that other people have the same freedom with respect to your contributions (being constrained) as you did

The philosophical stance of GPL is freedom at the individual human level - the only thing that actually matters if you are part of mankind. Yes, a society where you cannot "choose" to be enslaved is semantically less free than one where you can, but hopefully everyone agrees that for definitions of "freedom" which matter for human beings, the first society is a better choice.

Additionally, history has shown that such “choices” are often not exactly choices in practice

I have to admit, that I have higher expectations of people understanding licensing subtleties when they create software for distribution.

Because freedom is defined for the thing being licensed, it's not a human centric freedom of "I can do what I want with it."

It's from the perspective of, for example, the Software saying "I'm always free and never beholden to someone else's whims."