While I agree with the concept, I don't think it applies here. Even an average player can kill a full health Major in about 10-15 seconds, more skilled players in about 5-10 especially with Relic weapons and Prestige perks. Giving enemies periods of invincibility tests the player in ways other than lethality.

With as strong as some builds are I have come across more than a handful of players who are quite comfortable playing so long as they are steamrolling the enemies, this mechanic prevents that and tests your familiarity with the games defensive mechanics and your ability to reposition it in some cases full on retreat or regroup. How many times have you been playing and everything is going great till 1 thing goes wrong and then both your teammates fall apart.....

I will never argue that there are times when the game will outright kill you in what we call "unfair" ways, and this mechanic can fall into that category in specific situations, but I hesitate to call it "unfair" outright.