"RSS" wasn't very common to put on feed buttons. The standard RSS icon was normal, including in Firefox (where it would display on the URL bar when detected on a site). And commonly web pages linking directly to their feed would say something along the lines of "subscribe via RSS" or just "subscribe" with the icon.

People are definitely used to poking cryptic pictograms on contemporary UIs, and RSS clearly gives off an impression of something being broadcast.

https://en.wikipedia.org/wiki/RSS#/media/File%3AFeed-icon.sv...