> The cost could very well be in the millions for a single project

How did you come to this number? Something simple like giving the binaries with docs doesn't cost that much money. I'm not sure what you are referring to.

> how many hours of gameplay does that actually buy?

You seem to confuse the cost of continued support with the cost of giving it to the community. Nobody is asking publishers to continue support when they don't want to.

> But as someone who doesn't play games, why on earth would I want to encourage this?

You are not expected to support this if you don't care about it... But don't act surprised when you find out that some people do play games and they do care about them.

> You're suggesting a subsidy for gamers which everyone else would to pay for

No, that's not how it works. Not even close.