Apparently, you don't negotiate a big raise at Buffer. You prove that you've increased your experience level. The only thing I would add to the equation would be a multiple for "years employed at Buffer". Then they would be automatically handling raises for people as the stayed longer.
You could think you're in a meritocracy, that no one is getting an outsized deal over anyone else. The reality is that reviews and promotions will be subjective, gamed, or both. This is human nature. It might work with fewer than 100 employees. The military is proof it doesn't work in large organizations. The point and promotion system was endlessly gamed.
