Yes, that is ideally how it would work. Yes, they have infrastructure which needs paying for, but that infrastructure only exists in the first place so that they can take a cut of the donations.

> If the system was designed right any infrastructure could be distributed (put a bitcoin address and a notification URL in your HTML or something dead simple like that) and development could be sponsored by interested parties if needed. There wouldn't be any need for a fee.

You need a fee because otherwise nobody will do (or is doing) the work to implement it.

One would hope that if they get sufficiently successfuly they'd drop the percentage, but requiring them to achieve wider scale just to initially break even doesn't seem like it sets up good incentives to me.