I do see needs for something like decibels. It is a useful way to communicate an inherently logarithmic quantity. The real and IMHO only mistake is that it was described as a typical unit, while it should have been a unit constructor and specially treated in the SI unlike others. (Not in the SI, but the [milli]meter in mmHg etc. and `p` in pH---really p[H+] [1]---are other popular examples of unit constructor.)

[1] To be clear, I'm aware that pH and p[H+] are technically different. But that's orthogonal here.