uhhmmmm.... Sorry. No.
They've been lurking in the shadows for a very, very long time, LONG before the 2000's, using Usenet, dial-up BBS, AOL, Compuserve, and IRC, long before HTML became a thing. Especially Usenet and IRC. It freaking exploded on that scene. It was not very long at all that Arpanet went live after the end of WW2, after all. They've been connecting with each other in myriad clandestine ways since.
Some were even using C and Ku band gear as well as HAM gear (like slow-scan fax) to stay in touch with each other, and tracking down those various forms of backchannel communication was how we found a great many of the Nazi's that went in hiding.