I don't see much of a point. If someone makes a website and wants people to be able to send money to them for that, a link on that website should work just fine. I'm failing to see the benefit of a HTML meta tag related to that.

> I wish I could click a button to easily send a "tip" to someone who created something I enjoy or to browse other options for supporting them.

I believe most people invested in getting donations already have a similar button on their page.