I want to clarify my feelings about singular they.
(Sometimes I feel people are so busy fighting battles, they sometimes fail to notice that sometimes there is no battle happening.)
The singular they is a normal part of the English language. It emerged as a solution for indefinite number (not knowing whether there is one or more), and its use for indefinite gender (not knowing whether there is masculine or feminine or other) is natural and well established.
My difficulty with the singular they is stylistic.
For my taste, it too often matters whether the referent is singular or plural. And in my personal use, the failure of the singular they to distinguish number, is too often problematic for natural casual use.
The English language includes many, many, terms. I dont use every one of them in my own speech and writing.
For example, the literary term "s/he" is also a normal part of the English language, but I normally dont use it for style reasons. In this case, I find the use of the slash punctuation distracting, and while I assume the letters should be pronounced "she or he", that too I find distracting.
A gender neutral pronoun is in need − useful and significant. There are many different proposals for how fulfill this need. No doubt, singular they enjoys more usage than other proposals. But I remain unsatisfied with it.
Currently, I use the indefinite pronoun "one", which is also normal English. In all cases where the referent is unknown, it works great. But in contexts where the referent is known, it is awkward. Then I use the term "the one". It too is normal English, and is good enough for my purposes. But it too can get distracting, when it is almost like saying, "the she" or "the he".
I am still on the look out for a better gender-neutral pronoun.
Honestly, if English speakers accustomed to saying, "they is", making the verb singular when the they refers to a singular referent, that would help me enormously. In other words, "they" becomes an all-purpose pronoun for any number and gender, and the let the verbs do the work to help specify.