When is a prefix a word? When no one wants to say what the root is.
On a dating profile, a person says that they are trans. What information have they conveyed? How is a potential date supposed to interpret this?
The term transsexual is specific. To be born transsexual means to have a congenital defect in which the sex of the body and the sex of the brain (to oversimplify a bit) are out of sync. The cure is to change the hormone balance, surgically alter the sexual characteristics of the body, and allow the person to live as the sex their brain tells them they are. Male to female—straightforward. Female to male—more complicated, but the general idea is the same.
If the term transgender was non-specific, the term trans seems to be even more so. That seems to be why some people like it. They can convey that they are vaguely part of the already vague LGBT while saying almost nothing about themselves. "Trans" seems to mean anyone who is not male-bodied who lives as male in a societally acceptable masculine fashion, or female-bodied who lives as female in a societally acceptable feminine fashion, or anatomically intersexed (intersex, itself an overly broad term, is always separate from trans-anything).
You can't tell the players without a scorecard. In fact, you can't tell the players with a scorecard, because there are so many different scorecards.
People born transsexual, whether pre-op or post-op, whether lesbian, gay, bisexual, or asexual, even those who eschew "normal" gender expression, should avoid the non-word "trans" like the plague. If you were born transsexual, there is no need to obfuscate. And once you have successfully dealt with your birth defect, there is no need for any "trans" word at all.
Sadly, the non-word is everywhere. People who should know better use it and perpetuate the obfuscation, often in the name of some sort of inclusiveness or political correctness. People who do know better use it intentionally to obfuscate. When your purpose is to baffle people with bullshit, to deconstruct reality, to destroy the ability of words to convey specific meaning, then the last thing you want is anyone knowing what you are actually talking about.