^This. For a few easy ways to use them as suggested:
- Rule Machine ("Button Device" trigger is best for this) can use these commands with the "Start/stop raising/loweing dimmer" actions
- Button Controller (if you still have it, otherwise it's coming back in 2.2.0) can do the same as the above
- The community app Advanced Button Controller (ABC) can be configured with its own actions to do something similar
- The community app (disclaimer: my own) Dimmer Button Controller can also be configured to do this if you use the "dim while pushed/held" option
With all of the above, the most logical way to use this requires your device to send released events (which you'd use to stop the level change) after either a pushed or held event (which you would use to start the level change). It also requires your device, of course, to support these commands. Hubitat-native groups, unfortunately, do not, so you'll either have to resort to individual devices (may get a bit messy/laggy/inconsistent with a lot of them) or not use these commands there (stepping the level up/down on a press/hold isn't terrible).
Basically, it's a feature most dimmable Zigbee devices support as part of their firmware (and many others do something similar--I assume this was their inspiration), and Hubitat found a cool way to expose it for us to use if or how we see fit. I love it. 
