... every day they're spotted, posts are taken down, accounts are deleted, IP addresses are ringfenced ...
This is a manually intensive process the good guys have to keep up on a daily basis.
... yet for every effort we make to block them, they come back, and the whole thing repeats.
The sophisticated spammers can change, spoof, and redirect their IP address and automate most if not all of the process needed to repeat the assaults.
... In the battle of two people doing their jobs to opposing purposes, no one wins.
Unfortunately the spammers are overwhelmingly winning. For every one person who attempts to keep up with their automated attacks on a daily basis, there are hundreds if not thousands who can not put in that kind of effort.
One draw every now and then compared to thousands of checkmates is what keeps the spammers way ahead on the scorecard.