Honestly I’m surprised there aren’t more sects that explicitly reject Matthew by now. It’s the one that has the bulk of the “don’t be a dick” instructions.

Most of them seem to prefer John which can more easily be twisted into “if you’re a Christian you’re a winner and better than everyone who isn’t, no need to worry about the details, you’re already on the list”

The traditional attribution of Gospels to their namesakes may not be entirely accurate – it's plausible that it may incorporate material actually written by the Apostle Matthew, but also seems to lean on Mark and shares literary elements with Luke. There's a whole scholarly debate on it, called the Synoptic Problem.

For all we know, the author might have been someone else drawing both on the teachings of the Apostle Matthew and the works of prior writers, or entirely based on different works and simply attributed it to Matthew. Hence, "whoever wrote" is probably the safest attribution possible.