I never liked the phrase "ruthlessly prioritize" when it comes to scoping a product's features (or anything prioritization-related for that matter).

It's too violent. It implies that you should be unfeeling and cruel when in fact that opposite is true.

The best approach involves deepening your empathy to understand the problem. Then strip things down, clarify, and focus on solving the problem as efficiently as possible.

It's through caring more deeply that you can prioritize effectively. Being "ruthless" might get things done quickly, but it can prevent you from seeing whether they are the right things for the customer.