My solution? I think there is room for certain creatures/monsters to be rendered as setting-specific. In the core rules they have certain nebulous features that are not clearly defined and can only be explored through researching or encountering them in a given campaign.
If a GM wants the "fire creature" to be utterly immune to fire, then adventurers need to find that out one way or another, by finding someone who knows (if they know for fact is a campaign concern) or through trial and error in combat. This has the added, intended, advantage of restoring a sense of wonder in a game where too many gamers can just memorize the books in advance or who have no trepidations during encounters with creatures for which they, through other PCs, have discovered all they need to know for the new PC.
This is also why I like the idea of a PH with some well-known cratures (pack animals, regularly hunted animals, domesticated animals, etc.) a GM's Guide with some "classic" creatures and monsters, and skipping MMs in favor of setting books with the monsters and creatures indigenous to them outlined for the GM alone, along with options for how the GM can tailor them to their specific home campaign (the players in the campaign unaware of those specifics).