My guess is that they didn't care much when they made the 186/286 because it wasn't yet clear how big the PC would get -- and those chips did a lot to weed out

My guess is that they didn't care much when they made the 186/286 because it wasn't yet clear how big the PC would get -- and those chips did a lot to weed out bad programs (the once they didn't use caused INT 6) so they felt perfectly safe when they made the 386.