I found out one day that the keyboard combination results in an em-dash, so now I use it where I would use an em-dash. I never went out of my way to inconvenience myself learning both the keyboard combination and the knowledge of where to apply it together. I just happen to have picked up how em-dashes are used, and I just happen to have picked up the keyboard combination to produce them, and so sometimes I will produce an em-dash where one can be used. I also tend to produce en-dashes in the same way (Option-Hyphen) when I express a range, as that is a way en-dashes can be used.

These arguments are so weird. It's like you assume I set out to learn my exact workflow rather than evolving it over time. My workflow is the sum of everything I know to apply, it's not a single algorithm I set out to learn all at once. If you don't care then you don't care, I'm not trying to justify it to you, only to say I exist and that others like me might too.