Donations add up. If everyone did what you’re proposing, many projects would likely get no donations. Ideally everyone would donate a small amount to every project they use, which would all add together to be a sizable amount for all projects that are frequently used.
We aren’t all one person. We don’t need to all act as if we’re one. We should act as if we’re a community, because we are. Support all projects, and they’ll all get support.
That probably ideal, but it should still be spread out so the “less important” projects still get something.