It is highly regarded by some speaker designers, as evidenced by established manufacturers such as Castle.
The concept is that the sound emitted from the rear of the loudspeaker driver is progressively reflected and absorbed along the length of the tapering tube, almost completely preventing internally reflected sound being re-transmitted through the cone of the loudspeaker.
The lower part of the pipe acts as a horn while the top can be visualized as an extended compression chamber.
The entire pipe can also be seen as a tapered transmission line in inverted form, that is, widening rather than narrowing from top to bottom.
The driver is usually positioned close to the middle of the baffle or slightly lower.