FWIW, I’ve only attempted to scrape from the archive.org snapshot never musicdsp.org – mostly because I haven’t managed to catch it when it’s been up long enough to try. It wasn’t me, I swear! 
Glad you’re involved @bdejong!
Storing all the content as flat files sounds great to me. Seems like we could stick a wiki interface on top of that for editing if that would help automate the process of maintaining the site – still restricted by at least the requirement of having a github account, if we use github, and maybe further by using a github organization? Spam should be pretty easy to avoid by just leaving the public editing option off:
By default, only people with write access to your repository can make changes to wikis, although you can allow everyone on GitHub to contribute to a wiki in a public repository.
I just cloned a random wiki to look, and the repo is just a directory full of markdown files. We could then use the main repo to host whatever frontend we use to publish the wiki as HTML/CSS.
Otherwise I suppose we’d just do updates via pull requests with someone(s) in charge of merging the submissions into the main repo – or just grant folks direct write access to the repo?
The wikis seem perfectly suited to what’s being described above, and I think would work well as a place to hold all the content for the site IMHO. I like to edit my markdown offline in a text editor, but it couldn’t hurt to have a wiki-style editor attached for free for those who prefer it.