Reporting on cell voltages is not enough, cell bolt temperature, bypass current and accumulated bypass mAh give early warning to other characteristics about the battery pack.
Early warning prevents each individual cell from being permanently damaged. If an unusual cell bolt temperature is identified may be a loose bolt or another issue. Daily individual cell accumulated bypass current can highlight issues much better than cell voltage.
With additional sensors the battery supervisor can get the best possible performance whilst keeping the battery in service for longer. Cells of unknown history (second life) can be used because of the additional bypass power (8 Watts). Based on configuration ongoing adjustments can be enabled to compensate for the cells to keep them in-balance. With the additional bypass capacity the pack can be assembled without pre-balancing avoiding many hours of work and then instructed to conduct the initial balance whilst fully assembled.
Individual cell monitoring boards have a number of advantages that central system have to compromise. Without a complex wiring loom the system is modular and serviceable. Direct connection to cell using 2 wires (not shared as with central) allows the accurate compensation of the cables and enables smaller wiring gauge improving the safety. Installation is the biggest risk and features have been added to help whilst this happens. If wired up back to front (pos/neg) when fixed will recover without damage. Key to the installation the system will verify cell boards are properly working.