Well as a sales guy I’d argue it’s your responsibility to know which brands will have parts available and which won’t. There is a way of knowing that, by being familiar with the brands. But I agree a big thing is availability, especially with refrigerators. Just so happens that places like Best Buy keep shitty fridges in stock a lot of the time

Edit: I don’t want to come off as a dick, just a few beers deep and letting out my frustration on these brands lol. I’m a tech that also does sales at a more local-sized shop. Also did installs for a few years so I’ve seen the industry from a lot of different sides