That definitely makes a difference, you can choose which but by default it already selects one so some people won't even change it for convenience, however, that's not a thing on Mastodon so.. Also, a lot of those are mobile users and BlueSky has a lot more Twitter-like familiar UI than Mastodon apps (maybe I'm wrong and if so, point me to which one because there are so many.. there goes another issue and convenience out of the window for people who just don't care about searching and wants something to be done quick - so basically most of Twitter users that still didn't leave it or went to BlueSky)