Earlier quoted context omitted.
This is a good idea, but also the behavior will probably be emergent with the introduction of this feature - I can definitely see OSS maintainers offering logos/links in the README in exchange for monthly sponsorship. I bet we'll see the emergence of "Gold/Silver/Bronze" tiers too, just like at conferences.
Take a look at the Webpack page that GP mentioned. This is already happening
Heck, I've sponsored a number of projects back then as a teenager with a fledgling Internet business - with the express purpose of advertising to highly technical users I wanted to potentially sell to.
I'm not sure if it was terribly effective at sales marketing, but it was highly effective at marketing towards the types of employees I wanted to work with. I see sponsoring open source projects as more of a recruitment thing than sales thing these days.