Surely we should have some way of autobanning this level of spam....

How has this guy not been autobanned within two minute?
Just having a limit to the amount of new threads you can open when you're a new member would do a lot to prevent this already, but I'm not sure how much work that is with the current forum software.
Yeah, seems like a new member posting essentially the same post like 10 times should have triggered something. But this version of the forum is pretty recent, so maybe kinks are still being ironed out or something.
Edited: 2017-06-13, 4:11 am
Pretty sure myBB has the ability to limit the number of posts from new users out of the box. It should only require turning it on.
Thanks. Indeed there is an option.

Need to figure how to configure the Group Promotion. Upgrade to full member after say, 3 days, with 1 post per day.. is not ideal.

Reputation count would be another way, allowing existing members to promote a new poster with 1 -2 likes. (edit: I mean, to promote them sooner than the default).
Edited: 2017-06-19, 2:33 pm