It derives from an expression deep in the history of Usenet or e-mail (hyphenated), when hapless newbies (two syllables) were told by harried sysops to RTFM, read the f* manual.
And while it is being used now to simply reference the article, RTFA was originally used in the same way as RTFM. A way of expressing frustration to a commenter who should have read the fucking article first.
Indeed. I usually go with “OP” in non-frustrated contexts, myself.