Pratchett actually explains at length why Discworld history is inconsistent in The Thief of Time, thus providing himself with a get out of jail free card.
That book also contains a theological criticism of Buddhism, the religion of compassion, just as Hogfather takes a critical stand on materialism. I don’t know if Pratchett ever read William Empson, but Empson’s line about “all the good lies on which men long live well” resonates through Pratchett’s work.
And both Pratchett and Adams would agree with that, I’m sure. People should create their own stories, not inhabit other people’s.
A lot of the trouble in the world today is caused by people who inhabit other people’s stories and adapt them to their own ends.