I remember only one post by one member who reported he were told "this is the last time" when returning form a visa run to Uruguay, but I don't recall anyone posting that they were denied reentry.
Several years ago (at least) someone got a habilitacion de salida (ten day notice to leave the country) upon reentry, but that was because the border agent couldn't override a prorroga de permanencia issued at migraciones.
As far as I know, the only time that a member of this forum was denied reentry at EZE was because he had not paid the overstay fee prior to his previous departure.
I wonder how many North Americans, Europeans, Brits, and/or Australians have actually been arrested and detained for deportation by migraciones for having an expired tourist visa, especially since the inception of the DNU 70/2017.