If they could credibly threaten your infrastructure then it makes sense. If they have no real organized hacking capabilities then no. But the US has already attacked Iran through computers before with Stuxnet and is the world leader in software and networking knowledge so it does make perfect sense for Iran to disconnect its networks from outside.

You might also have to consider the propaganda campaigns the US could run against an Iranian population with web access. If the population isn't more discontent now than it already was, "secretly" replacing commercial ad placements on western websites with US propaganda when the requests come from Iranian sources could make them discontent or inflame them further, which is bad for the Iranian government.

The government of Lebanon is cooperating with Israel - it's only the southerners/Hezbollah in conflict, at least for now. The people of Gaza are cut off for the most part. The strict censorship inside Israel is what you should compare to - not as strict as a total access ban, but if you say the wrong things or take pictures of the wrong stuff you're going to prison.

My point is that the people of Iran aren’t the target of the disruption.

Remember when Ukraine used the Russian cellular internet to operate drones that destroyed numerous Russian heavy bomber aircraft? That’s what the US/Israel would logically be expected to do if there were wide open internet access in Iran.

This is obvious game theory playing out militarily, people only see political suppression but warfare is a totally different ballgame.

If China were waging large scale war on the US I’d expect the exact same countermeasures to happen.