How many of those are second passports for the benefit of people who wish to visit Israel without the added friction that Israeli stamps in their primary passport would bring?

Also, EU citizens do not require a passport to travel within the EU; by law, their national ID card suffices, thus making passports unnecessary for much of their travel.

Most Americans don’t generally visit Israel.

It’s generally very difficult to get a second passport.

In practice many still own passports, as they are considered as better proofs of identity when you travel.