Well nobody tried to use lead-acid batteries for storage of anything on the significance of grid base-load and replacing a huge chunk of transportation energy capacity.
For decades we have used lead-acid batteries in close to every backup power solution of any size, plus at least one lead-acid battery per vehicle. Of course we expect lithium-ion to surpass lead-acid in market size and number of deployed batteries, but the amount of lead-acid batteries in the world is nothing to sneeze at either.
