Well, it's not like there are not. I found only 1 website selling micro usb to micro usb cables. But it seems they solder them themselves.
So why it is so difficult to get them?
USB Cable – Why Are There No Micro USB to Micro USB Cables
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Related Solutions
No. XKCD made a good cartoon about how frustrating this is.
When you identify a cable that works well, you could mark it so it's easier to find next time, maybe by wrapping it with a piece of electrical tape.
Best Answer
It is likely for the same reason that USB A-to-A cables aren't common: host devices should always use different connectors than slave devices. The reason is that serious damage to the USB controller is possible if you plug two ends of a USB A-to-A cable to two USB ports on a host device (like into your computer). It is against the spec for a reason.
A-to-A cables (or cables as you describe) should not exist according to the spec, simply put.