I didn't mean to avoid your argument. You're of course correct, people who don't have the option of making something sellable might create free things to give away. Or they might not create the thing at all.

To my mind, if the result of eliminating that option is that equally good stuff gets created and distributed for free, that's a win (all else being equal). Conversely, if the result is that there's less good stuff created, that's a lose (all else being equal).

I can't tell if you're actually claiming that the result will be the former. I'm skeptical, myself. But no, I don't have any data I expect you to find convincing. Mostly, I find convincing the number of hours of work I see around me explicitly devoted to doing things in order to earn money, from which I infer that without a profit motive a lot of that work (and the associated things) would not get done. But I don't expect that to be a new datum for you, any more than the existence of wikipedia is a new datum for me, so I don't expect it to convince you.