Such A-to-A adaptors and cables always have been prohibited by the USB spec, but people built them anyway. A common usecase for “illegal” A-A cables i remember was connecting PCIe cards (especially GPUs and mining cards) externally to riser sockets.
An OTG setup needs all 5 pins of the micro-B connector. USB A cannot be used for OTG. If a USB-A port can act as a client, that’s not OTG, it’s a botched implementation.
Such A-to-A adaptors and cables always have been prohibited by the USB spec, but people built them anyway. A common usecase for “illegal” A-A cables i remember was connecting PCIe cards (especially GPUs and mining cards) externally to riser sockets.
https://en.m.wikipedia.org/wiki/USB_On-The-Go
In 2001 the directionality became kind of moot. Especially if you want to do attach something with an on-the-go host
An OTG setup needs all 5 pins of the micro-B connector. USB A cannot be used for OTG. If a USB-A port can act as a client, that’s not OTG, it’s a botched implementation.