No one is trying to emulate the play of people from 40-50 years ago. They are trying to emulate what their character would do in an unfamiliar situation. The reality is that all of us bring knowledge of the world and varying degrees of knowledge about the game, so we are always navigating the question "what makes sense for this character to do in this situation?" Acting, in other words. What I ask of my players is to try to immerse themselves in the story, to see it through the eyes of this person that they have created.
I know the rules of this game inside and out (I mean, there are folks on this forum who put my knowledge to shame, but compared to the median, I'm pretty expert). So if I play, I pretty much have to put a ton of that knowledge on hold if I am going to act in character, which for my taste in TTRPGs is a priority - it's how I have fun. So, for example, having my character do the wrong thing because it makes sense for them is a feature, not a flaw, and if it means failure, well, good stories need failure and challenge.
Iserith, above, has the obvious solution to combat challenges, which is to create new creatures as needed. But this can be a lot of extra work that not everyone wants to do, and might not be necessary, depending on what the players know (most of my current players are not interested in the rules at all; my spouse has been playing for years and still couldn't tell you that fire can stop a troll from regenerating, though they are smart and would probably figure it out quickly enough). And I can't know how much each player knows from other campaigns, reading on the internet, etc. So I don't think it is hard for players who do happen to have some out of character knowledge to put a pin in it for the sake of story logic, if that is the type of game we have agreed to.
Complete aside: the 10' pole thing tradition always bugged me, even back in the day. Have you ever tried walking around with a 10' pole? I have, more or less, while doing construction, and it's super inconvenient. The idea of a bold adventuring party cautiously moving through the dungeon with their 10' pole is the least heroic thing I can imagine.
Edit: in writing class, a question I always come back to with students is "what makes sense for this character in this situation?" That's my basic premise for my TTRPG characters, as well.
I run into knowing things my PC may or may not know all the time. So I just ask the DM "Does my PC know anything about this?" and then go from there. In my home game I'm pretty lenient, trolls are common enough that everyone knows what they are for example. I will also sometimes let people know things that the player doesn't know with an appropriate check. I'm typically pretty generous with PC knowledge, everyone knows you need fire to kill a troll and silvered or magical weapons to hurt a lycanthrope.
Again, this seems to come back to player skills and knowledge versus PC skills and knowledge. PC skill matters to me and in my game and I want to reflect that. Just because someone sitting at the table knows how to make gunpowder, it doesn't mean their PC can suddenly make bombs. Along the same line if someone is at the table and knows the MM inside and out I don't want them spouting out lore to everyone at the table. It's funny. I'm okay with players discussing a bit of strategy now and then at the table during combat because I assume that the group works this kind of stuff out during their downtime. Especially with newer players, as long as the person at the table verifies that they want the advice, I'm okay with people giving pointers. It's only an issue if someone telling another person what to do.
I played in a game that had a player that would literally pull out the MM during the game and start telling people relevant details. Not just the creature name but vulnerabilities, resistance, HP, AC, the whole 9 yards. When the DM didn't shut it down right away, the group (DM included) discussed it when the player went to the bathroom and told him to cut it out. It was disruptive of the flow of play but also took us all out of the moment.
We all have different preferences. I have plenty of puzzles and mysteries if I want them, that's not why I want players to RP their PCs. It's not that I'm expecting people to be surprised by the fact that it requires fire to kill a troll, it's that I want people to interact with the world around them as if they lived in that world.