Take the following with a grain of salt because the match culture among specialties greatly differs.
I agree, it's very tough for the applicant. I've had many similar discussions with co-applicants in the recent past about this, and we have come to the conclusion that there is no optimal solution in the current culture of the match and post-interview communications. You're absolutely right, there are programs out there that want you to send love letters so that they know they are ranking people who are in turn ranking them #1...but those are programs that generally have a reputation of advertising that they matched their "top X for the past decade" or something along those lines.
That being said, the vast majority of programs out there have no vested interest in advertising such a thing, and play by the rules: meaning they will rank who they like and let the chips fall as they may. Like
@operaman said, there are also a lot of programs who rank immediately after the interview and have an internal rule of not changing the rank lists afterwards...so love letters and phone calls mean nothing.
Something that my particular specialty has done to try to stem the tide of this post-interview communication shenanigans is ban post-interview communications all-together between an applicant and a program. Even thank you letters are considered taboo. Though I'm sure attendings talk to other attendings, I think this has worked quite well in forcing people to play by the rules and letting the match work as it should.