Why was having SDHCI so important? Became it made controller chips interchangeable to the rest of the computer/device? Or just because it meant people didn’t n

Why was having SDHCI so important? Became it made controller chips interchangeable to the rest of the computer/device? Or just because it meant people didn’t need to bit-bang manually to access the cards like I guess they had to with MMC before the host controllers came along?