You must have forgotten how they paid to put it in just about every installer, selected by default, and pushed it aggressively in every Google property. They may not have had to, but they used their monopoly position to cut the air off to every other browser. That's not ahistorical even if everyone seems to have forgotten.

We'll never know how things might have gone without that monopoly abuse. Maybe Mozilla would have had enough developers and testers to fix things without abandoning what made Firefox unique.