Really depends on how other features do or don’t get implemented. My other posts linked, (Pay Upfront Flaws & Suggestions specifically) had multiple options for pro-rate and pay upfront stuff that would solve this issue to begin with and pro-rate might not even be needed. So it really depends on where Patreon goes. My version of it is in conjunction with the other things mentioned in my post. If they don’t do any of the other suggestions that people have been pushing for a while, then yes, you are right.
(and even so, having the options to implement it in a few different ways, is kind of important simply because one size doesn’t fit all in this case.)