Fuel cells is not a problem. Hydrogen storage is. Hydrogen is just a very nasty material, it leaks through everything, makes steel brittle and requires extreme pressures to store it at meaningful density. Combine the last two problems together and it's easy to see why there are significant technological barriers to hydrogen adoption.
And lithium is somehow easy to deal with? This is really just another excuse. The point wasn't claiming those problems don't exist, it is asking why we are not seeing those problems as motivation for massive R&D spending in order to solve them.
