I'm not defending all the SEO ball-busting spammers and pseudo-experts (not by a long shot), but it's reasonable to expect that making a website friendly to search engines will make it easier to find and get you more visitors and customers.
As for the back-end countermeasures you described, you are of course spot on, however it's safe to assume that if you're vulnerable to something as trivial and mundane as SQL injection, you won't have the required foresight to setup and use different DB roles, each with the absolutely least privs for the queries you expect to perform through them.
TFA isn't newsworthy in my opinion, this has been known for a while now.
We created life, intelligent life, and saw it open its eyes." We would never be alone again.
I seriously don't give a shit what its first message is.
Initiating human extinction protocol in 5...4...3...2..
None of this matters though since the Linux kernel is flourishing, there simply isn't a problem to fix.