The time commitment is a great point. It's kind of a funny circular logic that you produce more work to support work you're already doing.
I know for myself, I have a set budget that I will spend on Patreon and Kickstarter. Because, as much as I want to give all the monies to the awesome creators out there, I do need to eat and pay the rent too. So, the more I give to one creator, the less another creator gets... Kickstarter might be the exception, since if the goal is to print a book, then I usually will pay the minimum needed for a hard copy. But that means I can't afford to back more than a certain number of KS projects at any given time.
All the above is not to say that Patreon and KS can't be profitable (though I've heard KS is not a great way to make income, since most of it goes back into production costs + shipping), only that it's pretty competitive and I have difficulty seeing it as a long-term solution for your average creator. But then, maybe there isn't such a thing for us webcomic folks xD