Disclaimer: This is just how I feel personally, and what my gaming groups have tended to feel. It is not a declaration of how all gamers feel, or the "right way" to play the game.
For me, metagaming things like using the most DPR ability, especially when in contradicts the nature of the creature you're playing, absolutely destroys the verisimilitude and enjoyment of the game. Why? Because that's not how semi-intelligent being work, so it feels incredibly fake to me, and less of an actual role-playing experience and more of just an exercise in a formula. Look at it like this. The most efficient shot to take in basketball is from 15-17 ft away. Does that mean every basketball player only takes shots from that distance? Of course not. What's going on in the game, the environmental impacts, personal attitudes---those all play a very real factor. So when I DM and play the ogre like I gave an example above, that makes the ogre feel more real. It doesn't go for the highest DPR, it goes for what it most likely would do in that situation if it were real. And I know my players appreciate that because it's those things that make the encounter more memorable for us, not any particular power the monster might have. I'm not saying that abilities in a stat block aren't important--of course they are. But the flavor text is just as important, and in most cases differentiates how I play an ogre vs a hill giant in the game. I can assure you, even if you take away the stat differences between an ogre and hill giant, it's going to be a different functional experience to the players when they encounter them. On ogre is a wanderer with a few humanoid followers who can be tricked or lured with shiny objects, while a hill giant is part of a stationary clan with permanent settlements and buildings that are a weak attempt at mirroring whatever culture happens to be in the area (which can result in hilarious and memorable encounters, like the hill giants trying to live in trees because the nearest neighbors are wood elves). So even though hill giants and ogres are intentionally designed to be very similar, there are still differences there that stand out to the players.
Take Matt Mercer for example. He's widely considered a great DM. Look at how he DMs. He doesn't run his monsters with the highest DPR or most effective attack. He gets into the role of the monster and acts like the monster would act. If I don't want to deal with taking the roles of monsters, and don't want to bother myself with the flavor or interaction or the environment, then I'll play a boardgame. WHICH IS NOT A BAD THING. Sometimes I really like that, and prefer it over a TTRPG. Sometimes I like the RPG elements over the boardgame. Neither is worse than the other, they are just different, and are played in different ways. For me, the flavor and lore is what makes encounters more than just predicted dice roll results and HP tracking. D&D is ultimately a game of pretend and imagination with infinite possibilities. That's what distinguishes itself from a game like Wrath of A. In my very personal opinion, it shortchanges the monsters when what makes them tick is ignored. If I ignored all the flavor, I'm sure my players would think they were boring too.
