What does "asexual" even mean anymore? Well, the definition of "asexual" is being re-evaluated by the psyhiatric community as a self-prescribed sexuality that precludes actual diagnoses.
"Traditionally asexual" people and self-identified asexual people are actually disambiguated in the DSM-V! Excerpt taken from the female side but the male side is nearly identical.
"For a diagnosis of female sexual interest/arousal disorder to be made, clinically significant distress must accompany the symptoms in Criterion A. Distress may be experienced as a result of the lack of sexual interest/arousal or as a result of significant interference in a woman’s life and well-being
If a lifelong lack of sexual desire is better explained by one’s self-identification as “asexual,” then a diagnosis of female sexual interest/arousal disorder would not be made."
Yep. If you self-identify as asexual, you can't be diagnosed as having a lack of a sex drive. We know what tumblrinas, shut-ins, and the willfully abstinent are but what about everyone else?
Well: You can have no sex drive and fall in love. You can have no sex drive and live a somewhat different but otherwise fulfilling life. Many people with SI/AD ask their non SI/AD partners to sleep with whomever they want so long as emotions don't enter into it. In the words of a previous patient "I don't like going to the movies either, if she wants to go to the movies with someone else, that's fine, just don't marry them afterwards." If you're SI/AD, you're a bit outside the zeitgeist and social structures built around sex but still a fine individual.
...On the other hand, if you say "I'm asexual" to decorate yourself, frequently wonder about the day you'll finally get laid, and masturbate to Superwhoniverse gay fanfiction 80% of the time you're awake instead of talking to real people... you're not "ace" you're "embarrasing." If living the life in this paragraph makes you sad and anxious, seek psychiatric help - its worth the money for even a few visits.
And most of all: If someone says they've been "diagnosed as asexual": either they don't understand what their doctor told them, or they're lying. Big surprise.