I would agree I’m doing good by FOSS projects (that Google themselves need or build) by paying Google, if I’m a Google loyalist.
My point is about the developer aspect.
Like mentioned above, some FOSS projects are “gifts”. These developers don’t expect any substantial gain nor do they expect to commit to maintain it. A very different thing to FOSS projects for which developers work on their free time (or even full time), where donations / sponsorships done directly does matter.