Re: Herd immunity
If there are 30 houses in my street, 20 have prominent burglar alarms and other physical security measures, and 10 don't, then which houses are going to be targeted. Herd immunity won't help here.
Or a herd of antelope, most of them are fit and healthy and can run fast, a few are weak. Which get preyed upon?
same will apply where hackers go looking for a victim, they will seek out and find the vulnerable, and herds won't help them at all.
The scenario where herd immunity might help is by reducing the number of nodes that can take part in a DDOS attack.