I can't say if it's commonly accepted wisdom, but I personally use dish soap on my cast iron when I need to (i.e. if it's too greasy). I think this is confusion that stems from dishwasher powder, which you should definitely keep away from cast iron (actually, a little might be OK as long as you don't run it through the dishwasher; not sure, never tried).

I've read that lye-based soap will attack the seasoning coating, but modern hand-safe dish soap will not.

If (modern) dish soap washes your seasoning off, it wasn’t seasoning, it was just grease and grime stuck to your pan.

It is true that dish soap used to be much more aggressive, and those soaps can cause issues for pan seasoning (and also for your skin…), but those soaps haven’t been sold (in any meaningful quantity) in decades.

Yeah it is.

I always use dish soap, and it will definitely take off any oil that hasn't been polymerised.

I think the people who believe this (and use cast iron) probably haven't seasoned it hot enough or have scraped off the seasoning close enough to the metal.

I use dish soap to clean mine after every use, haven't had any issues.

I heard that it used to be true but the chemicals in soap changed and now its safe to use, but I don't know enough to verify this.