RC doesn't even remotely limit spam. The largest abusers here have less than 1000 HP and can spam endlessly with little impact on their RC.
The RC system is completely broken and only affects new users usually doing legitimate transactions.
I've brought up a few times about revamping the RC system so it actually does something having scaling costs for operations. So if a single user posts 20 comments, they are fine, but it starts getting incrementally more expensive. This way users who spam 1000 comments a day can't do with impunity. You always have the make another account syndrome though, but RC currently doesn't do jack for any use case it was intended for. With RC delegation it is even easier to get around.