everyone is a he or a she

Not really. Most people are male or female, but that tells us nothing about whether they are a man or a woman. And the fact that you consistently keep confusing gender identity and biological sex tells me that you need to have a look at this.

as some individuals on this subreddit try to do by "correcting" other people's pronoun use

Preferred pronouns are not optional, mate. If you don't use them, you are not only being unkind, you are being incorrect. You do not have a better frame of reference about someone else's gender than the person themselves, and you do not have the right to argue their conclusions about their gender. And you most certainly do not have the right to choose what pronouns someone else can and cannot use.

It doesn't tell sexual orientation or gender identity, so why is it such an issue?

It does tell the gender identity. That is the issue. If you refer to someone as, say, 'he', that does come with the not so implicit idea that that person is a guy. If they're not a guy, then you can understand the issue with refering to them as 'he', right? It's both not nice and inaccurate. The same is true when to refer to a non-binary person as 'he' or 'she'.

The main problem I have with non-binary pronouns is the lack of consistency and the lack of understanding of the community. What is perfectly acceptable to some people is offensive to others, and every subdivision wants their own pronoun.

This is absolutely not true. 'They' is the standard pronoun. The new and made up pronouns will never catch on. 'They' already has. The mainstream press uses 'they' now. It was the word of the year last year. Like it or not, this is happening. You can stand by your views if you want, but know that if you do, the world is gonna leave you behind, just like it left behind the people who stood against the Suffrages, and the people who stood against the Civil Rights movement, and much more recently, the people who stood against Marriage Equality.

You are on the wrong side of history, mate, can't you see that? And it's going to be no more kind to you than it was to those people. Becoming that racist old grandma or grandpa, the one everyone dislikes and avoids, is that what you want to become?