I tend to look at the Gerber export as one more chance to see that everything is as I expected, and not just as it seems in KiCAD. Much like printing out text in a different font and size helps your brain to spot errors previously undetected, watching your Gerbers in a different viewer may expose some issues you did not notice in your EDA.
Might be nice for an extremely quick one-off but you'd need to be in a real hurry to skip over the 15 minute process that is Gerber creation and verification for those small boards.
I never use the native upload features. I never will.