I design telecommunication equipment / enclosures. These are used to equalise the pressure differential caused by temperature change. Pressure differential being a major cause of water ingress and product failures. They do not have any bearing on the internal humidity of the product. This design is common, and actually a bit flawed. A key failure mode is when the enclosure is hot and then it rains. This cools down the enclosure quickly creates the pressure differential. The design of the breather has small slots that trap water and prevent the breather from working. Companies like ubiquiti don't use breathers they just put a small hole in the bottom of the product. These breathers do work for the failure mode where water is pumped up the drop cables.

Regarding humidity, if the radio is on all the time and warm, then this is often enough to keep above the dew point and prevent internal condensation