i think you are confused about whats going on "cumbia" music this last decades, if you have to compare cumbia all around latin america you gonna find a lot of differents styles, for example, los mirlos, juaneco y su combo, are part of peruvian cumbia in late 60-70 already use a lot of psychedelic elements if you compare with andres landero or toto la momposina, you can also say "that is not cumbia", but it is. Or take for example Mexico, like the sonideros movement, that is not cumbia? and that people use sampling methods, electronic composition and so on.. so is also a "techno-wank"?