I would argue it's a sort of (nonrandom) proxy sample in the sense that they're ...

platz · on Feb 8, 2017

Ok, so if we make sure we're only talking about:

    > "what languages tend to be **asked about** on weekends, as opposed to weekdays?"

and:

    > "explore differences between **questions that are posted** on weekdays and weekends."

as opposed to the article title:

    > "What Programming Languages Are **Used Most** on Weekends?"

(emphasis added), is the problem then resolved?