There was also a variant of seeding that was dropping a Museum over someone's Gate. Sure, your game was overall safe. But you were barred from online play forever because you no longer had a door to the online space. https://twitter.com/Powa2xPuRiRiN/status/1246475654398464000

Likewise, something this thread didn't note is that seeding was invisible. When you put a seed down, it didn't pop up a building. They were non-existent until the next load. Which meant you could be seeded without knowledge and have a save forced by the seeder leaving town.