We do now regard 1-5 as all being made out of the same stuff that 7 is made out of. But many folks persistently felt that there had to be separate kinds of essences involved in at least some of 1-5.

Even before 1-5 were succesfully reduced they were still seen as part of 7.

They were just seen as parts of 7 with different properties to the rest.

Does that make any more sense?

It doesn't really clarify my main point of confusion, which is what you're attempting to gain by listing 7 (ie. pretty much everything) as a single thing to be reduced