I can't even start the game...

Not all proc sets crit?

Well Plaguebreaker does not crit.

Nobody reads the patch notes these days. Yes, they can crit now.

Item sets that scale off Weapon Damage, Spell Damage, Max Magicka, and Max Stamina can now again Critically Strike. Item sets that scale in order of magnitude, or based on additional modifiers such as Relequen or Zaan, will not critically strike. Many of these sets have received adjustments to their power as well. Below are the sets that can Critically Strike and have had their scaling values reduced by approximately 5%. If another number is listed next to a set name, that is the true value change:

Developer Comment:
Spoiler
Now with the hard cap to Critical Damage and Healing, as well as a new rule set that aims to diminish stacked item set burst potential, we’re moving forward with re-enabling item sets to Critically Strike when applicable. We decided to only target sets that are made for builds that are already building higher than base Critical chance, and have made additional changes to ensure they don’t become outright better than flat stat sets. This should significantly help viability of these sets in PvE, while many of the other targeted adjustments made should keep them reigned in for PvP environments. We expect these values or rules may change over time and we will be keeping a close eye on it.

https://forums.elderscrollsonline.com/en/discussion/comment/7433026/#Comment_7433026