Rx is not FRP, for sure, but even most impure FRP systems (like flapjax) are not really FRP given a pure definition.

"Reactive" is quite vague. The earliest programming systems labelled "reactive" were meant for expressing low level real time control behavior, but these days the word could just as well be related to UI or enterprise/web data processing (note, that the above projects don't really help with UI, they are more for the latter!).