The same argument, of course, can be made about a number of D&D classes. The D&D wizard has almost no relationship to many of the other wizards in fiction and myth. Bards and druids differ greatly from their inspirations. Warlocks and sorcerers likewise are a very gamist specific take that doesn't necessarily line up with myth and legend.My issue with this idea is that which witch is which?
"Witch" is not somehow a harder nut to crack than any of these others, especially when they can be modified and branched out with subclasses.
The reason we don't have it is almost certainly that TSR was first sexist (the attractive witch in the little white booklets wears a translucent top, because of course she does) and then scared of stirring up the Satanic Panic further.
Only people on ENWorld seem confused about what constitutes a pop culture witch, something any 7 year old can describe to folks in detail, if they want clarification.