You can't store electricity by itself. The problem we are facing is massive curtailment, i.e. massive overproduction of green energy that can't be utilized. There needs to be way of storing it at a massive scale. There is no feasible way of storing that much energy in conventional batteries.

If you can acknowledge that hydrogen is needed for dense energy storage and grid-level storage, then you should realize that we will eventually have a huge hydrogen infrastructure, and production capacity to match. That will create very cheap green hydrogen, and will mirror what happened with solar and wind.

Cheap hydrogen alone will drive large-scale adoption of hydrogen cars, regardless of the popularity of BEVs. A lot of people will choose hydrogen cars (possible e-fuel cars too, since e-fuels can be made from hydrogen) simply because it is akin to an ICE-car in usage.

The other point is that battery production is not green and is very resource intensive. Hydrogen cars let's you avoid that almost entirely. In the long-run, it will be pointless to care about efficiency when green energy becomes nearly free. That suggests hydrogen, not batteries, is the better idea.