If you think it's meaningless, it sure doesn't hurt.
There are usually some differences somewhere, especially at local levels (several Dem states have passed abortion rights laws, MN is doing a lot of other good state-level stuff).
Libs will flatten any conversation to "why aren't you voting?????" if you tell them you aren't. It's just not productive, and saying you vote but it will never be enough defangs a lot of what they would otherwise say -- at least lie about it!
I'm a pro-voting Hexbear because: