The bandwidth of a CW signal depends very much on the bandwidth of the modulation, eg the faster the keying speed, the wider the bandwidth.
"On the receive side, you can make your receiver as narrow at the transmitters oscillator". Completely wrong, and shows a fundamental misunderstanding.
Morse is a wonderful mode, but suffers from the lack of error correction which had made modes like PSK31 and FT8 so much more effective, especially in bandwidth usage.
> The sidebands of morse code carry no information and are incidental.
The sidebands in CW ARE the information. If there were no sidebands, there would be no information.
> When the key is down there is no modulation whatsoever.
No, but you can't keep the key down forever. The information is in the transition from Key-down to Key-up (and Vice/versa). Which is why the modulation envelope (eg bandwidth) has to be tailored to the keying speed.
> You can easily use a transmitter with Gaussian keying to reduce the sidebands to zero.
Gausian keying requires a Raised-Cosine envelope. It is this which contains the sidebands and the information, and causes the B/W to be widened.
"On the receive side, you can make your receiver as narrow at the transmitters oscillator". Completely wrong, and shows a fundamental misunderstanding.
Morse is a wonderful mode, but suffers from the lack of error correction which had made modes like PSK31 and FT8 so much more effective, especially in bandwidth usage.