"Stopping spamming has never been about stopping it all or creating a flawless system."
True, but having the solution be something they're already doing means it won't really tax them any further than they already are.
"Now in this case I believe that things such as a cool-down or longer post timers sacrifice little in terms of user-end functionality while forcing the spammers to try to circumvent these countermeasures."
A longer post timer would mean them needing more accounts.