It seemed to be so necessary simply because Trump didn’t offer his.
Again, no. Nobody created a rule for Trump. It is standard practice that every POTUS discloses tax returns in an effort to be transparent. Logically they have all disclosed it, because they have nothing to hide.
This is how you know the type of Trump supporter that has been brainwashed. It's the same type of stupidity as when JWs say that they are ok with the Watchtowell not opening their financial books, because they trust their leader.
Idiots and gullible morons who rather stay in step with their cult affiliation than knowing the naked truth about things.