Lower cost, safer, longer cycle times, better operating temperature ranges, etc. They are better in many ways. People obsess about energy density but that's not the only thing that is important. On that front the lower energy density is offset by the reduced need for costly and weighty cooling and safety mitigation.
For example NMC and LFP usually require complex cooling solutions with cooling liquids, heat pumps, hoses, etc. Peak Energy is planning to deploy a passively cooled battery in deserts. No protection from the elements. Freezing cold at night. Blazing sun during the day. Cooling solutions with all their mechanical components are the single most likely thing to fail and cause issues for storage solutions. Skipping that is a big reliability win and it reduces cost as well.