Actually, even Halliday, Resnick, and company provide a pretty good example of the perils of textbook publishing. That's into what, it's 6th edition? The entry level history text by Palmer and Colton (and now Kramer) is into its 10th.
I'm not entirely convinced that Halliday has ever met Walker. The "giants in the field," at this point, have achieved the status of textbook-by-committee simply because the publishers (which hold the rights) have established this particular approach as being extremely saleable.
And much of the time, they'd rather have the books edited to bring them up to date (but keep most of the same material and approach) than try something new and have to re-establish the market. Palmer has been dead for nearly ten years, and Colton has been retired for more than twenty -- but Kramer still revises the history book for them, and when Kramer is no longer available, we'll probably see the 12th edition come out as Palmer, Colton, Kramer, and Dinglefritz (or whoever).
I doubt I could make headway into the freshman physics textbook market, either. I can't go up against the ghost of David Halliday.