All business employees are redundant.

I recently heard from two companies (WhatsApp and Palantir Tech) which believe it is 100% redundant to hire business employees. No sales. No marketing. No business development. No customer support (though that's done by engineers). Just product engineers (and maybe an outside lawyer). A good product sells itself. Do you agree? For what type of companies does this hold true? And for how long? When (if ever) will this model bread down?