Defaults are incredibly powerful, Safari and Edge are the second and third most popular browsers next to Chrome. Chrome itself is a default on a lot of android devices. Speaking of android devices, Samsung Internet is 4th/5th most popular as it comes default on Samsung devices.
To say defaults don't matter because Chrome is used on Windows is a bit absurd. Chrome in 2012-2014 was still trading blows with IE even after the tremendous shortcomings during the Windows 8 and 8.1 era. This was a time when everyone was telling people to not use IE, and yet it retained ~20% use. Nothing like now where Chrome dominates ~70%.