iPhone X - overuse of the mechanical right-side button?

On my iPhone 7 Plus the mechanical button on the right is just used for sleep/power.

On the iPhone X, though, if I understand it correctly, it is appears to be used for three things: (1) sleep/power, (2) activating Siri, and also to (3) confirm purchases. Is that really true?

If so, instead of moving away from buttons (currently the button on the iPhone 7 Plus is not a mechanical button - it is haptic touch and perfect) Apple seems to have moved backwards, to require even more use than usual of a mechanical button. It's just another thing to wear down and break, like my pre-iPhone 7 Plus home button always ended up doing. And it's in an awkward position for what it does.

For purchase confirmations (and Siri activation) is there a way to do something on-screen, with a touch or force touch, and avoid using the mechanical button all the time, and still make use of Face ID?