Stuck out to me as well—author uses it only once apart from the title, and it's in scare quotes. Are they calling attention to the fact that it's not the usual form of the word, but then failing to explain why that's important to the subject of the post?

In any case, TIL that although "quit" is most common for past tense/past participle, "quitted" is sometimes included in dictionaries as an alternative.

It is valid in English to use quitted in this manner, but it does look and sound odd. Most dictionaries list quitted as an alternative simple past/past participle of to quit, but admittedly it's uncommon to see it in modern English. Usually quitted is used in the sense departed or left (following French usage), which, while perhaps archaic, is perfectly valid in English as well.

It's a new fad in SEO world. Gotta respect the hustle!

Same. I figured it's an ESL thing so no biggie.