I think the whole EQ advice thing ( cut more often ) could be based on a few things ; first , If you want something to be brighter , than it is pretty easy and seems natural to just reach for the boost knobs . And you will boost it (if it's there to start with )...... what if what you want to boost was tracked a little lower ( thus closer ) to the noise floor?? then you're boosting some noise along with it also , and , since you boosted , now you're using more of the total , overall power that's availible ....; ( a mix holds "5lbs" of audio so to speak ) . Also , boosting inches you closer to clipping
So here's the thing , you can get identical results ( make it brighter ) by subtracting some lower mids or the lows , which by a nice coincidence will give you a little more slack in the area that usually sucks up all the power/headroom anyways .... same results but with added side benifits...