I can't help but mention another Netziv which caught my eye. The Netziv has a number of diyukim in the text that he uses to support this thesis, but fundementally his argument is from a ba'alebatish kashe. Moshe instructs everyone not to go out during makkas bechoros because during a time of punishment the malacha hamaves may strike indiscriminately - asks the Netziv, how can that be? The malach hamaves must be able to distinguish bechor from non-bechor, so why can it not distingush tzaddik from rasha?
The Netziv writes a yesod that is found in many other seforim as well. During the makkas bechoros there was a trememdous hisgalus of Elokus. Davka the bechorim, those who were vested with greater spiritual potential, were affected by this hisgalus. To the Mitzri bechor who suddenly faced this revelation after a life of disbelief, the power was overwhelming and it brought death. Even a bechor yisrael, or one of the zekeinim, who also had great spiritual potential, was not necessarily on the level ready to receive such hisgalus Hashem and therefore also faced grave danger.
There is a mussar haskel here, which touches on something I wrote about before. I am always disturbed when I see people wearing clothes of yahadus that don't fit. If a guy has no background in gemara and halacha, why start learning Ishbitz or R' Nachman? If a kid in high school has learned 15 blatt gemara at most, why spend 15 hours a week on a chiddush of R' Baruch Ber? It is absolutely a sakkanah! People walk around with completely distorted perspectives in halacha and hashkafa because they have not covered enough ground to know what are positions are "mainstream" and what are chiddushim. That is not to say you can't adopt the a chumra from the GR"A or be inspired by an Ishbitzer. The problem is if you don't recognize the chumras haGR"A as a chumra but think it mainstream, or confuse an Ishbitzer with what might be the "mainstream" views of Rishonim in inyanei hashkafa. Davka those who are seekers of truth with great spiritual potential in the neshomos are drawn to extreme shitos and chumros before being grounded in lots of basic gemara, halacha, and rishonim.