"Citation needed" is a good thing, but "muh Reliable Source(TM)" is not, it's a variation of cherry-picking. Once a person has made up their mind, only information that feeds confirmation bias is "Reliable(TM)", whereas anything else is "biased and unreliable." Those are the people who fetishise footnotes. They are not worth arguing with unless you are prepared to chase a Gish-gallop, then go woozle hunting, and then have your interlocutor project their deliberate time-wasting onto you. Greg Laxative is a good example of that behaviour.

The subject of vetting sources is WAAAAY too complicated to summarise in a comment, but I'll definitely write about in the future.