that is because when you build it you will notice about half the sound getting through
And once again MC, that simply isn’t true. You might believe it to be true, but the numbers arrived via testing of the assembly’s don’t agree with you. It is not ’snotty’ to have an understanding of these numbers/construction assemblies. I’m in the architectural design biz, by code I must adhere to them at times, for wall separations of apartments as example (along with fire separation ratings). That is part of my job responsibility. And these various assembly’s are documented and tested (in a strict testing facility) so that they can be referenced to in conforming to various STC code requirements as necessary with the governing building authorities.