more than one Assertion query per request?

We are in a process to
evaluate SAML as part of our security infrastructure. We would like to send out
two or more Assertion queries in one SAML request by SOAP.  However the
SOAP binding restricts the number of SAML request per message to be no more
than one. (saml-bindings-2.0-os.pdf 3.2.2.1).  Could anybody explain to me
the reason for this restriction?

 

Thanks

Jason