The tubing can house a preamp for sure, but they also alter the microphone response.
A microphone is a "tuned system," much like a speaker or an antenna. While an antenna is unlikely to cover more than a few octaves, mikes and speakers do that. Everything about the structure and its housing impacts that.
Now they can be computer modeled, but the old mikes weren't, they were designed empirically based on lots of experimentation.
What if soy milk is just regular milk introducing itself in Spanish?