What is so wrong with saying there are old traditions and there are newer ones based off the older ones and saying they aren't the same?
Good question, which is why the answer gets it's own post.
Whats wrong with the view is that it arbitrarily freezes something in time and declairs it the true tradition. Look at the work of Joseph Lisieski: he more or less picks a moment in the Renaissance and declairs it the pinnacle of magickal tradition. Everything before it was building up to the magick of that moment, and everything afterward was a degradation of the true tradition. To this end he has people attending Latin masses, stealing leftover eucharist from church garbage and all kinds of nonesense.
Why that time? Do we have any evidence that the magick of that period worked any better than any other time? No. There were no teleporting and flying mages gettting mad rich off the gold made by the philosophers stone. There are stories about incredible things, but there are stories from any period. Hell, there are even some stories about little old me that arent believable.
In Tibet, the Gelugpa and Sakyapa were did exactly the same thing. They wanted to re-capture the Buddhist Tantra of India that had been wiped out by the turks. Anything written in Tibetan was new-fangled crap.
The problem in both these cases is that its museum keeping, not magick. Magick grows and evolves with the times. To a large extent, the idea of individual traditions is a grammatical fiction. They dont really exist because the people that originated them would have given their eye teeth to interface with people from different traditions that they could borrow from. In fact they did.
Look at the Papyrii which can be seen as one of the prime roots of both the Western Grimoire tradition AND the various traditions of Witchcraft. Do you find a clean homogonized tradition? NO! You find a clusterfuck of religio-magick that draws on everything from Christianity, Judaism, Egyptian Paganism, Greco-Roman tradition, and a hundred other things. Look at any one of those elements and you will find a similar conglomeration of elements. Its like putting matter under a microscope; what may appear as solid and whole is really made up of millions of individual parts and a whole lot of empty space.
Now, make no mistake, I appreciate people digging into the past of traditions and recovering the babies that were tossed out with the bathwater. People like Frater R.O., Aaron Leitch, Skinner, and Peterson are doing an immense service by recovering parts of the western mystery tradition that had been abandoned by Levi, Mathers, Wescott, and Crowley.But that doesnt negate the contributions of those four. cat yronwode is doing similar recovery work in the field of Hoodoo, recovering parts of the tradition that had been killed from slavery, racism, and the impact of pharmacutical companies*. That doesnt negate the work of everyone that did something new or synchretic with Hoodoo.
When things that were forgotten in a tradition are recovered or re-emphasized, it should not be seen as a turning back of the clock, but rather yet another new development in the continuing evolution of the art.
*In the old days, rootworkers would get their herbs from the same places that doctors would. When drugs started to become synthesised in a lab, various occult vendors and african american cosmetics companies started supplying herbs for magick. They were less than dilligent about really suppliying what was asked for by their clients, instituting a policy that yronwode terms "green for green, brown for brown".