That is a very poor analogy.
If WotC puts out the PHB, and then puts out the MM, and then puts out the DMG, that is analogous to putting out FotR, TTT, and TRotK. These are books in the same line that are obviously intended to be used one with the other.
A better analogy would be, if FotR TMP is put out on DVD, followed by FotR Director's Cut, followed by FotR Ultimate Director's Cut, followed by FotR Ultimate Final Director's Cut, etc.
You might prefer one over the other. I, for instance, prefer the LotR extended versions over the theatrical releases, but the release schedule is still clearly motivated by potential profits.
This is not necessarily a bad thing by itself -- I happen to like the remastered Star Treks -- but not recognizing that it is so, and that it is different than splitting the same edition/novel/story into chunks, doesn't bolster your position.
The analogy was poor on purpose - the OP claimed that the RPG market was literally the exact same as the book market and claimed LotR never changed or had any additions added to it. It was a pretty dumb statement and I was making light of it.