i think it’s right associative. the author wants good apps to use as examples (and since he’s comparing these against an assumed default, ”good” really means “better” here). the author can’t find many of these better apps, so he’s requesting more of them: more better apps.

i admit it’s confusing to have in the headline (easier to make sense of after he’s covered the background), but the language is sort of constraining in this area. he probably wanted to avoid “more good apps” as that would be mistaken for “better apps” (which isn’t exactly what he’s after). “more better apps” is less ambiguous, but only so long as you expect that the author isn’t one to intentionally misuse language.

I assumed it was a reference to the slang movie title "Mo Better Blues".

More betterest.