^ Maybe like 72% about recent discussion is semantics mostly. ;p
Scarred veterans of many a PnP battle have grown accustomed to calling them healers as supporters or whatnot since time immemorial. People who got exposed to group-play in RPGs through multi-player in video games know the same people as healers. When we speak of the " trinity",every single healer class/role since forever has had it's share of support, migitation and Crowd Control. Just like every damage dealer, too, has had it's share of CC,buffs, debuffs. And ofc, no tank has ever been literally 100% just about tanking and nothing else.
Regarding evolution of Healers and morphing them as some irrelevant side-tree of support in PnP;
It is interesting how the evolution has actually been reverse in video game world;
World of Warcraft(and Everquest before it I think) began with " Support classes" being 4th clearly definable&recognizeable identity among ones we keep calling trinity. Druids, for example, were not awesome healers in their own right but would deliver great deal of utility and enhance the overall healing of raid when working with " actual" healers. Much to woe of everybody,Blizzard did it's own share of streamlining and erased the support classes by turning them into more " traditional" healers or damage dealers.