I disagree that you can pretty much do whatever you want with them.

Modern conveniences such as a dishwasher coupled with a focus on healthy eating (less fat) result in poorly taken care of cast iron pans.

Dishwashing soap these days are also a lot more efficient than they use to be. More and better surfactants eat away at any pantina that develops.

Yes you can drop a cast iron and nothing will happen to it. But to get eggs not to stick to it takes a bit of upkeep.