Another perspective: Working memory for equations becomes tricky once they span lots of lines or multiple pages and long variable names make this worse. Same r

Another perspective: Working memory for equations becomes tricky once they span lots of lines or multiple pages and long variable names make this worse. Same reason one often sees I1 + I2+I3+I4 in estimates. For the moment you actively don't want the mental overload of all the details. You just want to know that there are four terms to be discussed, now forget about all others and let us start looking at the first one. Similarly long notation/names just do not work well on blackboards/whiteboards.