> but I could see how they might be alien and uncomfortable to someone that has only ever experienced mobile interfaces

They are different devices. Just because you can drive a sedan does not means you can drive a bulldozer. Or playing piano qualifies you to play the organ. So going from touch and a small screen to keyboard/mouse and a bigger screen, you should expect that the interactions will change.

Exactly this. The “one UI to rule them all” paradigm has been a persistent, recurring flaw for decades. It probably hit its lowest (to date) with the exhortations to “mobile first design”. The motivation for that was reasonable: conventional desktop UIs of the time didn’t render on mobile. However the ensuing “mobile first” instead became “mobile only” - and consequently wide screen displays with buttons the size of elephants.

Phones and desktops are so radically different that your sedan/bulldozer analogy seems like shades of grey. It’s more like taking a Saturn V rocket to the local shop for a pint of milk.

true, but ~all new users have a stronger mental model of how their phone works vs. big-screen devices.