Crit reduction is underrated, most of the hits that one shot you are actually critical but people don't use it on gear because it's kinda annoying to craft on gear, and resistance comes first always and it's easier to craft
The node on tree you mentioned is not used bc it's generally useless, you would have to mark idk how many enemies at a time, makes get consumed or expire and then mark them again, just not worth when you can one shot the mob anyway
I for example build into the crit reduction on the tree, there are 2 nodes on the north part of the tree that give 25 % crit bonus reduction each and they are used quite often by people
Additionaly one of the meta uniques for warriors is a body armour that provides huge armour and taking no damage from crits.
Pob also doesn't calculate crit reduction, at least not correctly, a friend of mine messed around with trying to min Max ehp and crit reduction, while a huge benefit in actual maps, had little to no impact on the numbers