It is truly worth spending the time learning these shortcuts as they will speed things up and you will be able to spend more time actually doing what you intend instead of searching through software. This means there is a lot less time to forget your ideas.
Forget MIDI control surfaces, mastery of
this tool will suffice for most of your work.
Of course, in Reaper, if you don't know the shortcut, you can find the feature in the menu, and the shortcut is conveniently displayed alongside it. Can't find a shortcut for a specific function? You are able to set one yourself.
It is obviously not just Reaper that wields this powerful capability. Most modern DAWs have this ability to varying degrees. I highly recommend using this feature as another feature to base your choice of DAW on.