Studied math a long time ago and one of my profs was proud about not going into the details. He said "Once you did something 100 times, you can go and say -as easily observable- and move on."
I loved that some of the proof solutions in the back of mathematical logic book said, "Observe that ..." as the start of the proof. Our little study group definitely did not see how what followed was an observation we would have made.
I was an algebra major at the turn of the century and I hated that attitude.
For the prof, yeah, easily observable. What about the students who try to absorb that particular article? You already have to balance the main topic in your brain, and you get these extra distractions on top of it.
