Silly clickbait title, which the author even admits up front.
UDP and TCP have different behaviour and different tradeoffs, you have to understand them before choosing one for your use case. That's basically it. No need for "Never do X" gatekeeping.
My apologies if the star in front of "never" was added to the title in the last ten minutes after you posted your comment. But that star is clearly there to indicate "fine print ahead"; in a title, it's pretty obvious that it means that the article is not about to "gatekeep" people out of UDP. (In fact, at the end of the article, the author suggests to use QUIC which, you guessed it, is based on UDP.)
UDP and TCP have different behaviour and different tradeoffs, you have to understand them before choosing one for your use case. That's basically it. No need for "Never do X" gatekeeping.