We must move in different circles, I have yet to meet a TS who did not know at a very early age that their body did not match their gender. Some of us have tried desperately for numerous years to suppress this knowledge and have therefore (wrongly) self-identified as non-TS cross-dresser, but in my experience eventually we can all identify signs from early childhood. In my own case, I fought the knowledge for roughly 47 years, but the Gender Dysphoria was present for the whole of that time.
I do not understand why someone who as a child cried themself to sleep every night wishing that she could wake up with the right body would not eventually want to "go as far" as SRS to use your term. I was loved for who I am, I just didn't know that I could talk to my parents about what was wrong at a time when virtually no-one had heard of transsexuals and anyway SRS certainly wasn't available unless you were rich.
To the best of my understanding a TS is born TS and does not progress from fetishist through cross-dresser to eventually become TS.
I am not trying to deny your experience and woul dbe interested to hear from some of the TS you have met who were not born that way, but developped from being a male cross-dresser to being a woman in a man's body.
My own experience might be covered by your statement about some people starting at stage 4, because there has never been anything remotely sexual about my Gender Dysphoria, but it has stopped me from assuming the role of a husband because I could not conceive how I, a woman, could be someone's husband with all that that entails.