Those are pretty different things though. The IETF is sort of a mailing list where stuff happens and text files come out of it so the next guy can read it to make their own ircd... and a pretty large number of popular protocols don't have RFCs. I'd say mostly programmers who do sockets would know what the IETF and its RFCs are so it doesn't really have any actual marketing weight logo-wise. OTOH, someone who downloads something that advertises itself to be an IRC client and it doesn't actually connect to anything IRC, the soft will just be collectively deleted, downvotes will be given and bad reviews will surface.
USB forum (and the rest of these types of things) defines the standard through consensus between the paid members I'd think, but also provides a bunch of device class specific utilities, test suites, a registry to prevent VID collisions, etc. Consumers look for the logo and they'll know it will plug in and probably work (not as much in a lot of cases now as it was when it was new I'd assume, since it is absolutely ubiquitous, except maybe for 3.0 and the other specialist ones).