Why? Maybe the 'they' signifies a recognition of some gender or sexual fluidity within them and while right now the identity as either he or she, they also recognize that that may not always be the case.

Further.

We always talk about individuals fitting to the gender presentation as though those general presentations are static. I'll remind you that high heels were originally made for and worn by men.

So what if the accepted gender norms shift so much to extremes (a very real and observed possibility in modern times) that individuals who otherwise ife tidy within a gender no longer feel comfortable doing so?

Identifying as they/them is a valid solution to the bombardment of marketing propaganda and media presentations of genders.

At least, until the general populace recognizes that these normalized extremes are too much.

Let's be clear. It is undeniable at this point that media presentations and marketing propaganda that push 'how to man' and 'how to woman' have eroded people's self esteem and been detrimental to our overall mental wellbeing.