Why?
I absolutely love A, B, C; they're critical to my project, the maintainers put pour their own time and effort in, and I want to make sure they get my support. Dep D is pretty good and I wouldn't mind throwing a bit their way too. E is some wrapper lib (or maybe a company-backed package) that I don't care to support monetarily.
Since I want to support 60-80% of my deps, something like StackAid sounds attractive; I don't have to set up and maintain individual (potentially recurring) donations to each. I set up $100/mo to be distributed, feel good about doing my part, and go back to work.
Turns out, only E is collecting their StackAid, for whatever reason. My $100/mo is all going to them. Nothing is going to any of the others, let alone the packages I definitely wanted to support in the first place. I think I've donated, so I don't think to seek projects' alternative donation channels to get the money into their pockets, so they don't see a dime.
The only solution is to go through all of my dependencies to see which ones are actively using StackAid and decide if it's a sufficient set before donating through them.
As a product developer wanting to support I would have to make sure all my dependencies accept StackAid before I'd even use it.
As an open source developer I'd be pissed to find out that my project had $1k in funds held by some rando company in my name.