I've been using homebrew for years and have never heard of this. Maybe the reason there's only 285 patrons is that the patreon page has not been promoted in any way that I can remember?
“How dare they inject advertising into a critical command line tool that I use to get paid money!”
“It’s inexcusable to promote your own financial success when someone types brew upgrade”
“No doubt they’re blowing the money on burrito delivery in SOMA”
“I’ve been a $1 Patreon since they launched three months ago and they haven’t implemented my favorite wishlist feature!”
“If they can’t do it for free, they should give up and shut down and let someone fork it.”