As long as there has been spam, there have been ways for spammers to get around any roadblocks put up to try to stop it. It's constantly evolving, unfortunately.
I know IB and mods are doing an awesome job attacking spam each time something crops up, as evidenced by the thread in the Tech Support forum. Until they know the next method of attack, it's impossible to plan for everything.
All of that said - I visit some boards that have restrictions like needing to post in a "Let Me Introduce Myself" type of forum/thread before being able to post anywhere else on the site, so if the spam REALLY becomes a site-wide problem, something like that could be implemented to at least corral it to one forum. Just an idea.