Earlier quoted context omitted.
Possibly related: SO requires you reach some number of upvotes before you yourself can upvote. When I use SO and try to upvote a useful answer I'm always reminded that I don't have the privilege of upvoting.
I have given up on participating on SO because more often than not I am told I don't have enough reputation to do something (I don't know if it's commenting or giving an answer or giving an upvote but there are some questions for which answers are wrong or need some updates and I can't participate. So I just don't by default. I think I can't upvote on some stack and I find this weird).
https://stackoverflow.com/help/privileges
You need 15 points to up vote which means you need to have received 2 up-votes yourself on either a question or answer or have edited 7 questions/answers and had those approved. It's quite easy to hit those numbers. Once you have 1000 points (I think) on any site and you join a new site you get 100 points by default which means you always have those base privileges wherever you are.