I think one of the biggest reasons is that people want an easy shortcut, when in reality the best thing to do is simply to use the pan a lot, and respect that it is iron and that iron will rust if you strip away the protective layer, so don't do that.
Yes but sorting out the sense from the nonsense is effectively impossible. You can find arguable authorities/experts that will say whatever point of view you want to find and validate: Soap is bad, soap is okay in small quantity, soap is fine; Use salt and oil to rub it clean, don't use salt and oil because you'll dig into the seasoning; you have to strip it down to re-season it, no you don't. It goes on and on. Literally everything about cast iron care is contested, and by people who are professionals in the kitchen/cooking business and "use them all the time and get great results" so they must be right, etc etc.
If it can't stand up to ordinary dish soap and even a bit of salt scrubbing to get out burnt bits, it is not properly polymerized and therefore not fit to cover the inside of my pan.
So keep using that pan, including washing it by hand, until a proper strong seasoning is achieved. Some things can't be rushed.
Leaving it wet doesn't do you any favours either though.