The point is, there is no evidence for the authors you claim and some evidence for the names that are on the gospels, not to mention church tradition from fairly early puts the names to them. In the very least there is as much evidence for the traditional names versus the names you gave, although Nicodemus is a stretch to say the least; Matthew is a far more likely candidate behind that he was an actual disciple and apostle. And if the majority of reputable and relevant scholars say there is no reason to doubt the names of the books, then there is no reason to believe otherwise.
It has nothing to do with scripture versus tradition. In the end, if the apostles and close companions of them wrote the gospels, it is irrelevant which ones.