every customer complaint is N customers lost who don't say anything

"the biggest impact" isn't knowable so a bird in hand is worth more than whatever might be in the bush

If you have M customer complaints, and each one risks a differently-sized N customers... you better try to triage that vs just playing whack-a-mole with whatever comes to a random engineer first. I've never seen engineers plow through a bunch of 0-or-1-customers-would-actually-churn-over-this papercuts because it was easy and it feels good - the customer mentioned it! i fixed it! - while ignoring larger showstoppers that are major customer acquisition and retention barriers.

Nothing is knowable in only the same way that plans are useless but planning is essential.