@drewdevault the contributors are not ignorant and CHOOSE to play along.
They could have forked but didn't.
The non-free angle is entirely up in the air: it's possible, I totally agree on that but it's not guaranteed. Only certain types of software is susceptible to being closed as a SAAS.
GNU requires CLA for entirely different reasons but it's (more or less) clear why they do that.
In both cases the contributor chooses to contribute under the rules set out by the project or fork or not.