Because they didn’t want the retribution that would follow. That’s what protection looks like. Assured destruction when it’s not mutual is pretty motivating.

Lol, classic American exceptionalism.

Iran didn't attack the desalination plants because that would amount to actual warcrimes - and they care about their public perception in the broader community of nations. Unlike, of course, Israel and the USA, who don't mind turning a few schools and hospitals to smithereens.

You might call this "assured non-mutual destruction", and of course it helps that the US is located away from Iran's immediate neighborhood, but destroying the lifelines of the GCC countries would assure an economic collapse globally that the world has never seen before. Imagine something on the lines of oil at $300 a barrel, zero fertilizer, zero semiconductors, zero plastics, the works. And Iran could just as easily turn Israel to glass, with a death by a thousand papercuts (or drones, whatever your flavor). Of course, all of this at a huge cost to itself.

Sure, but we still couldn't have stopped them with our vaunted carrier-based power projection, or with our exhausted ABM capabilities.

US Naval doctrine has been a paper tiger ever since that Millenium Challenge exercise.

It was more son that they have space to escalate. It was strategic decision. They did attacked those when their plants were attacked.

US does not have capability to destroy them. It can make lives of civilians hard, as it tried, but foreigners attacking civilians dont make regimes fall.