The build server then builds the whole application and runs the unit tests. I might do this once a day if I'm mostly thinking rather than furiously typing or ten times a day if it is all flowing perfectly.
It's not just the kids who do this, I'll be 61 in a couple of months. On the other hand one of my colleagues who really is half my age prefers to complete the feature and only commit to the build server once the whole feature is complete. He uses TFS shelvesets to make sure he won't lose anything.
More generally I don't see the connection? I'm not making commits to show off my cool code to my colleagues. I'm making commits in case I want to revert specific changes later.
I learn to commit more frequently every time I realise I need to undo something manually because my history is insufficiently granular.