Highly astute question and I think it may not! (Thanks also to Julia Specht (juliaspecht.com) for pointing this out in a beemail reply as well.)
This shift in mindset from punishment to taxation has happened gradually and I think it’s time to rethink the messaging here. A lot of the webcopy encourages riding the exponential pledge schedule to levels that are blatantly beyond taxing!
So I’m thinking the UI should guide users on this better, maybe by explicitly asking for your thresholds on what’s a tax you can stomach vs your Motivation Point vs something so scary you’d rather flatten the bright red line, or, G-d forbid, cheat.
Your idea of just making the pledge a free-form amount is not crazy either.
And today @clivemeister has another nice angle on this question: