MX Blue, MX Green and MX Clear all have a separate slider component of the stem that when pushed past the actuator point it makes contact with the bottom of the stem, which gives an audible click before the rest of the stem bottoms out:
Every switch can be bottomed out...what he was saying is that if you can touch type, linear switches can be very quiet in comparison. I use linear switches and some soft o-rings under every keycap to further dampen sound and make bottoming out softer when that happens. That said, every switch when returning to the default position makes a noise as stem makes contact with the top of the housing. This is still quieter than bottoming out, which is still quieter than the click made from switches with sliders. The audible click from these switch types offers a confirmation that the switch has been activated for touch typists, so it's mostly about preference and if you need that confirmation or not.
It's similar to how a buckling spring switch works in that when depressed, the spring is propelled into the switch housing at the same time as the actuation is made. When you hear the click, you know the switch was activated.
