By December 2003, DIME had lost out, in competition with Message Transmission Optimization Mechanism and SOAP with Attachments.
[3] Microsoft now describes DIME as "superseded by the SOAP Message Transmission Optimization Mechanism (MTOM) specification"[4] The standard was intended to be an improved version of MIME.
Because HTTP is connectionless, it would then entirely lose the possibly huge amount of data that had been sent to it, just to accept or deny the challenge.
The response to the challenge could of course succeed, at the expense of sending the data twice, which if it were huge rather defeats its point.
This did not subvert the security aspects, since the challenge would still occur, merely that it accepted that binary traffic was the norm on that port, and did not give numerous false positives.