It's a sliding scale. You have to pander to them to some degree - there's no choice. But it takes grit to refuse to e.g. branch your core code or otherwise compromise your architectural integrity.

The problems are when the sales team does not appreciate the downstream costs of just letting this one patch in. And when you're a struggling startup, sometimes they're right and the social proof of the deal (and the revenue) make it a good choice to compromise your principles this once.