Back in the days of the Acid tests and when vendor prefixes for experimental features were the norm, and a visit to caniuse.com was often met with disappointmen

Back in the days of the Acid tests and when vendor prefixes for experimental features were the norm, and a visit to caniuse.com was often met with disappointment, discretionary users cared as much about a browser's layout engine as the application's surrounding chrome and features. But as web engines have been moving closer to feature parity (as well as Chrome and Firefox's combined dominance of marketshare), the bonus features of the application are rising in importance. (Some) people want their bookmarks, their synced passwords, their addons, their (sometimes-captive) integrations; this is the space that Edge competes in now. The same applies on iOS, for slightly different reasons. On iOS everything is slightly different, you get the same rendering engine every which way. There, the only way to differentiate yourself is by extra features.