So that perverted nutcases can operate outside of our attention until they are ready to burst forth (after adequate recruitment and organizing) making demands for parity with decent and normal folks before making demands for preferential treatment and then for dominance.
Polyamory seems to mean nothing to most hearers. Fornication, adultery and group sex are too familiar for the feelings of safety and comfort of the "polyamorous." They still need some hiding time before they start holding Polyamorous parades and such.
So that perverted nutcases can operate outside of our attention...Bungo!
oh,, oops.., I mean BINGO!