This is kinda what the Basic Attention Token is in the Brave browser.
You can either tip directly/manually, or setup a monthly payment that gets split automatically among the places you most read. It doesn't require the creator already be a member, but rather it holds the funds until they register, or until 90days have passed.
They've also built in some significant privacy features so that no one can determine who/what you're donating to. Though this leads to one of the contentious issues as refunds are not possible, so when the above mentioned 90 days passes without a donation being claimed, the funds go into the "User Growth Pool" which basically means they are given out to new people joining BAT as an incentive to join.
The big controversy though was exactly the issue of not requiring people sign up before they started accepted BAT donations to them. They had a system of showing if a user was 'verified'[0] meaning they were registered to receive the donations, and nothing would be shown if they were not verified.
This led to an issue where Tom Scott commenting that Brave was taking donations on his behalf without his consent. [1]
Imho that was hugely damaging to the potential of BAT and I think really stemmed from people who didn't use BAT and didn't understand the Verified/Unverified aspect of it. They've added a Non-Verified statement and icon now to make it explicit, but the damage has been done.
[0] http://se.ri0.us/2018-12-22-184516548-9adee.png [1] https://news.ycombinator.com/item?id=18734999