Don't recall this being stated or implied. Only that it is unnecessary.simonh said:Were talking about one page of material in the core rulebook being superseded by a full supplement. Hardly game-breaking, campaign shattering stuff...
Stating a rule set is incompatible is not berating the rules - only addressing a reality.
If two sets of rules generate different results for the same datasets, then they are, by definition, incompatible.
Mistakes happen - hence, for RPG books, we have errata.
It is sloppy when such simple, fundamental things like this are overlooked - since it is so easy to address the fact of a difference up front by stating the rules are conditional/optional or superseding.
Not having the book, maybe the OP is mistaken or the book actually made provisions for any difference. But the only way any of this gets addressed is if someone brings it up.