Mythicism doesn’t account for gaps in what Paul writes better than mainstream scholarship does.
It just fills those gaps with something different, something which is at odds with what Paul does explicitly say in places.
People who did not previously know about a historical Jesus would be left with questions after reading one of Paul’s letters. And people who did not previously know about a celestial Jesus would be left with the same kinds of questions after reading one of Paul’s letters.
People want information about other people. And when they believe in gods and celestial beings, they want information about those too.
And so the claim that somehow mythicism makes better sense of the gaps in Paul’s letters is not just bogus, but completely bogus.
And that anyone finds the claim persuasive, suggests to me that they have not given sufficient thought to the matter.
A good biography cannot include every detail, but it must provide enough. And a good myth may not include every detail, but it must provide enough.And so surely the best explanation for the lack of historical and/or mythicial details in Paul’s letters must be the genre, and not the fact that he thought of Jesus in historical terms, mythical terms, or both.
And while one can certainly read mythicism into the gaps in Paul’s letters, there is nothing in those letters that requires one to do that, and some things Paul says make it much harder to do that. It is most straightforward to fill in missing information that fits with Jesus having been a Jewish person believed to be the messiah who was crucified, as Paul explicitly states, not to mention that this fits with the slightly later Gospels and all other relevant sources as well.