50 reputation is only 5 upvotes, and there's an association bonus that means you start with an extra 100 rep on every site once you establish yourself on one. Also, you can always comment on your own questions. The requirement only applies to commenting on others' questions.
It encourages "farming" in my opinion. I'm sure it's a net positive (maybe) and keeps spam down but... it's weird. They want you to contribute in a certain way before you can contribute in the way that you're most likely to encounter (randomly landing on a question from Google during the middle of a busy day, drop a quick note, try to move on, etc.)
On answers you get 10 for upvotes, on questions you only get 5. Then you can also get 2 at a time by making edits to others' questions/answers to improve them (this only works up to some limit, you stop getting the bonus past that).
> Then you can also get 2 at a time by making edits to others' questions/answers to improve them (this only works up to some limit, you stop getting the bonus past that).
The limit is 1000 reputation earned from edits or 2000 reputation total, whichever comes first.