When you turn it on, that is zero, if you move it around by hand before issuing the start command it is still at zero.
In CNC where you screw your material down always changes, the thickness (Z=0) is always different. End stops and homing add significant complexity to your jobs. If you look at the crown page it say where you start your machine is zero.
If you back up and think about homing you have to first home (which means deciding where 0,0,0 is) then you have to tell the machine to move to your material (where that may be) then start. You can skip all of that by putting the bit where you want it to start by hand and just hitting go. You should always be surfacing (so you know where Z zero is), and you typically never use a factory edge so who cares is X or Y is not at exactly 0.
So you picked the only example where this takes one extra step. I propose you home it to an object of a know thickness and tell you CAM to use a cut depth of that thickness. Still less work than end stops and they will still result in you getting a dot as it homes Z.
In what way, they are not emergency stops (unless you change the firmware, I highly suggest you do not do that), They are only active during a G28. All my firmware have the end stops enabled for homing.