There are already some good answers here, but I will just reiterate a few.
The #1 reason is to keep things as simple as possible.
It will just add clutter.
It also helps the animators see what is important.
“Hey this scale channel is unlocked what does it do……oh nothing”
It does add to the file size, which won’t be much unless there’s hundreds of controls (which is often the case), but file size isn’t a big issue.
It can slow down animation playback depending on what the computer has to draw. The more windows you have open and the more curves that are visible, the harder your computer has to work to playback the animation. Showing curves during playblack does slow it down – so having curves that do nothing is just an extra ball and chain the computer has to draw.
The display of curves has improved dramatically over the past 2 major releases, but keeping the playback as fast as possible is something we always want to do in animation. If animators can’t view their work in real time, they have to playblast. This slows them down and adds significant costs.
Hope that helps clarify things.
