Hate to break it to you, but WiFi most certainly is RF. :) ... it just happens to conform to standards (802.11b/g/n), has a higher symbol rate, and includes methods to avoid and/or recover from collisions.

And yes, if you try to operate the same IR based device from two remotes at the same time, conflicts are unavoidable. But I don't think anyone is asking for that to work flawlessly.

Now often that happens as a side-effect because an IR blaster may be beaming a signal meant for one to device to multiple, but that could be addressed via IR routing.

By ignoring the problem you're just letting the RF remote manufacturers off the hook. They could do a better job to avoid interference (of all types), so far, they've chosen not to.

While you could probably improve your home WiFi by going through all the mechanations that you typically do with a MRF unit, most people don't and never notice it ... because while throughput may be reduced by interference or a poor signal, WiFi knows how to recover from it.