That really isn’t how it works. They hold less charge, but you can have more of them and weight isn’t really an issue. They can also charge more gradually, making the dynamics really different.
A battery bank at home can be a good solution to grid balancing, eg if power is cheaper during the day or night, or if you have solar. Water storage systems aren’t very efficient and need lots of space, but there are people who do it. You can also compress air into a cave. Batteries are just something that are cheaper and more space efficient than other solutions.
Centralized batteries work as well, though they don’t do anything if you have lots of grid failures.
