It's an argument that being a sound company is not a requirement for being a disc jockey. Someone else can provide the gear.
Getting stuck on the gear is typical of someone who's DJ talent isn't strong enough to stand on it's own. That person will compensate by making the conversation all about the gear rather than the social, relational, or promotional goals of the event.
I suppose this is where DJs who step out of the club have the advantage because, they already understand that the gear has nothing to do with why they get paid, and the conversation stays on topics that matter to the client.