I've never used any of these voice assistants. Do people find it easier to yell "Hey Siri, set up an alarm for 1 hour" vs going to Clock app and setting one? Not bashing anyone, genuinely curious.
A lot of what makes Siri easier than the various apps is easier input and multitasking. Input can be simpler as some apps can have fiddle controls for adding very precise values. I am often doing something else while using Siri to do something. My phone may not be in my hard or even in the same room.
I have Google Hubs in every room not just for the excellent audio casting, but to keep my phone out of my hands more than it absolutely needs to be.