I don't think that is correct. Unless you're
claiming that MacTCP was
not "built in", which you could claim, but John Veizades would probably
have something to say about that. It was certainly available long before
1995.
I don't believe neither MacTCP nor Open Transport were standard parts of
MacOS until, in fact, OS 8. When I installed 7.1 and 7.5 (gag), I had to go
scare up separate networking stacks. I don't remember if 7.6 had anything
built in but I'm pretty sure Open Transport was still sold separately then
too.
OpenTransport first shipped on the PowerMac 9500 with System 7.5.2, and
was bundled with System 7.5.3 and later. A standalone installer was
available for System 7.1 and later.