Because that's been busted for some time. A lack of easy point-and-click GUI RTMPE dumpers does not mean the encryption scheme is unbroken.
Tools which have a copy of the well-known constants
extracted from the Adobe Flash player are able to
capture RTMPE streams, a form of the trusted client
problem. Adobe issued DMCA takedowns on RTMPE recording
tools including rtmpdump to try to limit their
distribution. However in the case of rtmpdump, this
led to a Streisand effect.
Because that's been busted for some time. A lack of easy point-and-click GUI RTMPE dumpers does not mean the encryption scheme is unbroken.