Aubrey Waddy dropped me a line right after the Good Word mentor appeared. Here is the gist of our conversation:
“Thanks for the daily exploration and today’s word, mentor: good fun as usual. I read the Odyssey and the Iliad as a boy, in English I hasten to add, and they were great adventures; I’d forgotten Mentor.”
“Your use of the word advisee, however, prompts me to ask whether you can address the abominable word attendee. I pedantically make a point of using attender, but it’s a lost cause.”
This confusion is a result of the two different meanings of attend: “to take care of” (intransitive) and “to go to” (transitive). There is an old tendency in English to use (1) -ee (standee, devotee, retiree) and (2) -ant (congregant, claimant, and applicant) as the personal (agentive) suffixes for intransitive verbs, words that cannot take a direct object in some sense. The suffix -er at one time applied only to transitive verbs like drinker, eater, player, words that can take a direct object.
Notice, however, I say ‘tendency’ not ‘rule”, for the tendency is dying out now in favor of a general suffix -er: runner, swimmer, walker. This probably relates to the difficulty in keeping transitive and intransitive verbs straight. Run, swim, walk may all now be used transitively, as to run the course, swim the river, walk the dog.
Now, getting back to attendee. Someone who attends to someone might be called an attendee but for whatever reason attendant seems to be preferred, probably because this word is a borrowing from French. To attend a meeting, however, implies a transitive verb, suggesting attender the correct form. So you are right in claiming that attender is more appropriate than attendee; in fact, I see no room for attendee under any guise with its current meaning.
But don’t expect a change any time soon; this word is too firmly embedded in the vocabulaty now.