Gateway is a loaded term, it has too many negative political/social connotations. It would be the same to say using enemas is the beginning of a slippery slope towards ever more and intense/deplorable(?) fetishes. Because that is the intended, but unspoken message most people will get when they see the terms 'gateway' or 'slippery slope'. That it refers to something that should not be done or that is deplorable or even illegal.
So, perhaps not the best term to use for enemas. Perhaps 'introduction' might be a better word to use, as a positive thing.
"Slippery slope" has a kinky ring to it though.
i so agree with this and others who have pointed out the connotations associated with "gateway." It's a shame it has been coopted, because in another, maybe more literal sense ("gateway" also has a kinky ring to it), it could fit?
i see our "kinks" as individual expression of need/want. Some cultures use all sex as a control, a means to assert agenda. Kinks become a sub category of that, an even more powerful way to manipulate and control people. Ironically, it's a form of Domination, eh?
i believe enema, or any other thing that might venture into or touch our sexuality, can be a gateway in a good way. i do not think it, or any other kink, is causative, i think acceptance of kinks that appeal to us individually can be a gateway to deeper discovery of who and how we are. Sharing those "kinks" with others can help us connect more deeply in relationship.