You is describing the neologistic use which leads to the singular use of "they". It not be regular English grammar, however, to say that there am no plural any more. They dost be a plural form, and using it to refer to a specific person is still grammatically plural, and uses plural verb forms. English hast plural pronouns, whether though preferrest it or not. It be singular ones you have a problem with.
<back to normal English>
"You" is a plural pronoun long relegated to singular use in English. It accompanies plural verb forms even when used to refer to one person. So while John goes to the store, you (individual) go to the store and all ten of you (y'all, in southern, or youse in Rhode Islandish) go to the store too. If someone doesn't want to be a "he" or "she", then he may want to be a "they", and thus always plural