Why do Wi-Fi have overlapping channels?

Question

WiFi

Very often I see in the recommendations for setting up Wi-Fi networks advice not to use intersecting channels. The argument is that it is better if the routers work on the same channel and see each other than when the adjacent channel is simply perceived as noise.
The question is - why then so many channels are provided in the standard? Why couldn't it be possible to leave only non-intersecting 1, 6 and 11? The same is true with automatic configuration - why do routers climb into intermediate channels and create the picture that we constantly see in high-rise buildings?

Answer 1

1. In addition to Wi-Fi, these frequencies can be occupied by other networks. It is likely that channel 1 will clog me with noise, and you will have to go to 4.
2. In addition to the channel, power is also of great importance.
3. In reality, the router does not completely occupy all 5 channels, but much less. See ieee 802.11 spectrum mask.

Answer 2

An article has just been published on Habré that gives an exhaustive answer to your question. And also to all other questions related to WiFi channels and their choice.

Answer 3

She inspired the question. It says that it is not necessary to cross the channels, there is a call to bet on 1,6,11, but there is no explanation why then other channels were invented and used.