If they want to distribute the contributions, they will have to make it clear up front.
"I hacked this wood and made a spoon."
"I hacked my breakfast."
I do get that there was at some time a group of people where it had a clearer meaning.
Absolutely clear and honest would be something lie "we intend to take your free labor, declare it our property forever, make money of it en put it in our own pockets".
No one would consent to that, so organizations use weasel words or bury it in the small print. Mostly, they just obfuscate the consequences. Especially the "property" and "money" bits.
And yes, that is a "trick", even though by some definitions they are "clear" about it. Thousands of lawyers make a good living off that distinction.
Let's rephrase everything: People should be aware of Github's lack of communication before they start messing with this too much.
(Tom Preston Warner has already stated that Atom's core will not be open source)
Or are they already accepting contributions?
Or is it a case where Github's size/reach makes them unique in this at scale?
So if its too ethical to pay for quality software, just think about your own job, you get paid, right?
Sublime is not free, still people create packages for it, for free.
Do you mean that if the code is open to everyone, the software should not cost?
Kind of weird, using open source software to create software to make money, but not being able to sell software for money if its opensource.
Software can be free (as in freedom) and open source while still not being free as in beer (ie, charging money).
davexunit is commenting on the fact that the Atom editor is proprietary (non-free) software, which has nothing to do with whether or not they are charging for its use.
Then, read this explanation from Eben Moglen about why the FSF does copyright assignment. https://www.gnu.org/licenses/why-assign.html
Long answer: Some GNU projects require copyright assignment to the FSF. The most well known example would be GNU Emacs. However, unlike GitHub or another for-profit business, the FSF is a non-profit charity dedicated to free software. Additionally, there is a clause in the CLA to ensure that contributions cannot be made nonfree. I have made some small contributions to a handful of GNU projects at this point and I have not yet had to assign copyright for any of them.
The copyright assignment situation with the FSF and the GNU project is dramatically different than the potential situation that I've described about GitHub. I hope I've made things clear.