With conventional prints there's the problem of "silvering", where the black silver in the emulsion starts to turn metalic silver. I've only had this happen with prints that were dry mounted with Kodak or Seal dry mount tissue on what was most likely NOT acid free board, and the prints date back to the 1960's. The silvering is around the edges of the picture so I strongly suspect a reaction to acid in the mount board. Most of my printing was on Kodak Polycontrast rapid until DuPont Varilour came out in 1968 (?). I mostly used that until DuPont sadly decide to get out of the "sensitized products" business a few years later.
At this point I have no idea which prints were on Varilour and which on Polycontrast because all the prints weren't made at the time the negatives were shot. I used Kodak Hypo Clearing Agent and probably a bit more than the suggested wash times, then dried them on fiberglass screens. I still use the same screens, which get hosed off from time to time.
I remember reading someplace probably at least twenty years ago that just a tiny bit of residual hypo in the print will keep it from silvering. It seems that we can wash prints too well also!
Back in the early 1970's I was visiting my home town of New Bedford, MA and there was like a flea market at the annual Scallop Festival. An elderly photographer, A. F. Packard, and his daughter were there selling his collection of vintage double weight 11x14 prints of old square rigger whaling ships for $10 each. I guess that'd be like $50 now. I bought a couple of them, dated 1906 and 1918. He'd been the photographer for the New Bedford Standard Times back then. He told me that whenever a ship came into the harbor after a voyage of two or three years he went down to the docks and shot a photo for the paper. Now I wish I'd been able to buy all of them! They've been framed and hanging on my living room wall ever since, and are still in great condition.
As for RC prints, I started using it for contact sheets and prints for publication shortly after it was introduced. They were processed in the conventional manner, not run through a stabilization processor. They still look like new.
I suspect that when the resin coated papers first came out Kodak, Ilford, and the others were just covering their a$$e$ when they said the prints weren't long term stable. At the time there was no way to know. It was a brand new product while fiber based paper was century old technology.