What? You may see a popup once, on first run after switching default, just like every other browser.
You also get it on OS upgrades. But seeing as these are only once a year this seems like not too big a deal to me.
Haven't seen any of these pop-ups thrown at my face in 3 years of using macOS. Also, your default choice for browser is respected throughout the system unlike Windows.
Web links in search not respecting my default and opening in Edge is one of most disgusting things I've seen.