Sure, write up stuff that supports your referral back to the original notes, or makes corrections and additions - but don't get rid of the original notes or replace them with interpreted copies.
The original article was talking about students learning in lectures. One might presume that the learning process ends with students being tested in a situation where they have no notes of any kind?
If that's true, then there's no point holding on to "the originals", because on the day of the test/exam/whatever, you won't have access to them anyway.
In essence, transferring knowledge from the original lecture via the written notes to ones memory?