Stacked combo units with a top-load washer on the bottom definitely exist[1].

Whirlpool makes them by combining washer assemblies from Clyde, Ohio and dryer assemblers from Marion, Ohio.

(It's not necessarily the most convenient way to do things, but it is also not a fiction.)

[1]: https://www.whirlpool.com/laundry/laundry-sets/stacked-laund... [scroll down]