So ranged carries get tenacity now from 21-9-0 masteries

Agreed. Most people don't realize that 2hp5 is 24 hp per minute or about the same as you get from the utility tree for picking cookies and the extended potion duration. That mastery was utterly worthless.

Not squishy as fuck ones, no. The 10% less duration isn't going to make a huge difference. When you play a marksman, you die when you get hit with 2 CC abilities. That's it. No discussion.