I was trying to engage with your argument, not the specific terminology, I apologize for being unclear!Friendo, the increased prevalence of non-spell magical abilities relative to spells in monster statblocks post-MMotM makes anti-spell abilities less effective than they were pre-MMotM. If you don’t want to use the term “metagame” to describe that… ok I guess? It doesn’t change the actual content of my argument.
My point is that having the effectiveness of anti-spell abilities change in the mechanics either requires the table to ignore that change in the lore of the game world, or else to have that change in IC effectiveness be reflected by a change in the lore of the game world. A OOC dynamic environment where certain spells and abilities change in mechanical effectiveness creates a problem for tables that want the in game lore to reflect the mechanics but don't want to retcon the setting or have an IC dynamic environment where characters are aware that the utility of certain spells changes over time.
For example, at a table that wants to switch to using new-style caster statblocks, Globe of Invulnerability has changed OOC from blocking almost all PC caster and NPC caster offensive abilities to only working at full effectiveness against a small handful of people in the game world (the PCs and any NPCs built using slots)--all the other casters' primary attack bypasses the spell's protection. Such a table could: (1) choose to simply ignore that change and have PCs and NPCs make IC decisions on whether or not to prepare/learn Globe of Invulnerability as if the spell was still fully effective against all casters; (2) retcon the setting so that the perceived IC value of preparing/learning Globe of Invulnerability matches the new mechanics, and rebuild all PCs and NPC casters so that they can make a new IC decision on whether or not to prepare/learn the spell; or (3) have an IC event that explains the change in effectiveness so that casters are IC aware of the change and can take IC actions to adapt to it as best they can. At my table, at least, none of these options are palatable.
More broadly, because of the myriad approaches that tables take to connecting mechanics to in-game lore, there are far more complications to having a dynamic PC vs NPC metagame in an RPG than there are in games without as strong of a roleplaying element.