LOL it's not bothersome. That person's job is literally to answer questions from applicants. And your theoretical is just that - it's theoretical fallacy. 5,000 applicants don't call every year and wouldn't call even if people presumed it to be "okay" to call. A lot of the time, schools will tell students that they'll hear back in a certain timeframe. If that timeframe passes, and you've paid egregious application fees, the school should be ready to field calls from applicants.
Please understand that it is not that person's job to just answer the phone, at least in the adcom offices that I know. Adcom offices often work with a very small staff. The person in our office who answers the phone is a high level admin who has to wear many, many, many hats to ensure that those who are invited have a great interview experience - and we interview students 3 FULL days a week, plus a night before option, and MSPE's might have 2 days. The admin person makes sure each interview day runs smoothly and on-time, answering all questions of the interviewees throughout the day, schedules interviewers, ensures best matching of interviewers with applicants, finds emergency replacements for interviewers who cancel, finds places for off-site interviewers to interview students, chases down interviewers to turn in their reports, finds students for overnight hosting, dinner the night before, and tours, etc. etc, etc.
I can tell you that though that person has a multitude of responsibilities, they have no input in who gets invited, and little direct contact with the people who do the inviting (a grp of admission committee folks who mostly work remotely with the head of admissions to review applications). If this admin does have a negative experience with an applicant, they can make sure that person is NOT invited or accepted, so though I doubt most people on SDN would be rude, it can't help and could only hurt. YMMV, but since our school does not review applicants in any real order by date of completion, the person can not even comment on a predicted pre-II decision date. It would depend on how fast the two assigned reviewers get to the application and turn in their pre-II scores, and then those need to be compared to the other applicants' scores that are coming in. Crystal ball needed in our office in order for that person answering the phone to have any decision dates for pre-II students. I do think that once interview season finished, the person will have a lot more time to answer the phones for those who are WL and understandably have questions about that. (Our school used to be transparent about telling students whether they were top, middle or bottom third of WL, which was pretty helpful.)