There is also a certain segment of historical thought (that I happen to belong to) that feels that NVN allowed the Tet offensive (and the follow-on attacks) to continue so that the VCI WOULD be exposed and eliminated.

I've also always felt that there were at least two distinct conflicts going on simultaneously in Vietnam: one with NVN, one with the SVN VCI/Nationalists, and possibly a third with NVN's attempts to absorb Laos and parts of Cambodia.