I'm not going to get into how one identifies as TS. There are so many arguments from those that say they are TS, but live and function as males. It gets pointless.
Misty coined the term a couple years ago. Transitioner. Although another label but I think if we define the criteria that a transitioner is one that is socially, transitioning to live their lives as the opposite gender 24/7. Timelines aside. The objective is coming out to family, friends, work. Changing legal name and gender. Then the term had meaning.
I notice lots of posts end up with part timers, those wishing to live socially except for... (Fill in the blank). Get bent out of shape and feel as if their experience is either not credible or valid. While I'm sure some of it and I don't discredit their experience. It simply is not the same as those that do come out to the world. Change their legal name and gender. Go to work or seek employment as their target gender. As I read these various posts. It occurs to me that the biggest differentiator is work. Coming out at work is what separates us and our experience. The experience is different. Many of those on the part time fence say we are belittling or elitest. It is neither. Our experience is different. The daily challenges are different. We all have different levels of intensity. The means by which we find a place of balance to mitigate the GD to give us the best quality of life. But at the end of day what we have in common is we live our lives 24/7. Or they are actively pursuing that goal.