Depends, blanketing Ben Gurion (or any airbase) with parked aircraft on the tarmac with carpet munition is a really bad day.

But yes, against protected targets cluster munitions do not achieve much.

If you have relatively few low-precision missiles, using single warheads means you are risking achieving NO damage (easier to intercept, a good chance that it will hit nothing), with a cluster munition you are guaranteeing at least some damage.

I think Iranians are mixing both types of warheads.