Maxperson
Morkus from Orkus
Not at all. In fact I posted the exact opposite of that:
You posted the opposite, but the logic you used applies to monsters as well.
To elaborate yet further: whereas some versions of D&D direct new players to read the monster section (eg Moldvay Basic) and others are silent on the matter (AD&D, 3E, 4e); and whereas it is a ubiquitious feature of D&D play that one encounters the same monsters in new campaigns, and hence knows the weaknesses despite never having had this particular PC deal with them before; most modules that I'm familiar with have a bit somewhere near the start which says Don't read this if you're going to play it as opposed to GM it.
The existence of skills designed to let the PCs know monster abilities and weaknesses proves at least for 3e and 4e, that the players are not intended to just be able to pull the knowledge out of their rears and use it in game.
The game provides no rules for actually dealing with this, because when the game was invented it was taken for granted that players, being good wargamers, would do what you call "metagaming" without anyone looking for an ingame rationale.
The game provided skills for it in 3e and 4e, and 5e.