Part of the problem there is I have guys just absolutely insist at me that a microwave "can't" be vented outside so they don't bother to install a duct, and tell me that in order to vent outside you "have" to get a hood instead. This is obviously bogus.

This also leads to the inevitable Contractor Special where a duct was there, often when the user is replacing an old hood with a microwave, but the installer just shrugs and slaps the microwave on the wall as-is where A) it is inevitably too tall and now way too close to the stovetop, and B) covering the duct outlet while still recirculating back into the room. Whenever I unearth one of these in my travels it makes me want to track down whoever the hell installed it and then punch them so hard they come clean out of their socks.

People are for some reason hyperfixated on getting appliances off of their countertops, which is why the over-the-range microwaves became so prevalent in the first place. (And then they all immediately filled the spot where their countertop microwave used to be with a countertop air fryer instead, but that's a whole different discussion.)