There seems to be an important point that people are overlooking here. This is, that descriptions of the path are not fixed objective realities. The path is the removal of a number of defilements. If one defines these defilements in a different way, that will increase or decrease the number of things to be removed. If two things were previously removed together, but are now to be removed one after the other, then an extra stage has appeared.
This means that the path description depends on the teaching being given to any particular group of monks. There can easily be two, or more, descriptions of the path, which fit different sets of instructions for the monks. These paths can appear to be different - but they are essentially the same. The end result is the same.
In other words, changing the teaching method requires also changing the path description. Its not really about 'doctoring' or corruption of the teachings. Two different descriptions of the path can both be correct, in their proper context.
Best wishes, Vincent.