Not only is this not an "Old School" D&D thing, it's not even a "Common Game Thing". This is 100% a DM Thing. And in my view, a Bad DM Thing. It is true that a great many players will argue the rules.....IF the DM lets them. All too many players will be happy to stop playing the game AND force everyone else to stop playing the game while they argue that their dwarf in full plate can swim against a strong current of an underground stream with his shield and "two handed" battle axe held in one hand with NO check what so ever for three hours.
But again....that is IF you let the player do that. I made a simple house rule ages ago: players can only bring up things after the game or any other time we are not actively playing the game. Of course, few players feel the need to come over on Sunday and argue that a dwarf in full plate mail is just like a submarine for three hours.
There has been a shift.....but it's because of the massive change in life styles. Life was a LOT different in the 70s, 80s and even into the 90s. Though sure if you lived in a deep urban city you just went to the corner store to buy food...and that is not so different in 2023 except that store is a Dollar General. But for everyone else:
Kids had to learn a TON of stuff. Just take cooking. Come home from school and you wanted a hot dog? Well...you basically had choices like "boil a pot of water on the stove" or "make a clean wood fire and hold the hot dog over it". Microwaves were not yet a house hold thing. Needed some soap? You had to make it. Needed some candles, you had to make them too. And on and on. The massive mass marketing of goods was not quite nationwide. Sure you could buy some candy at a store....or you could make candy at home. Like Rice Crispy Squares....people have been making them forever....but they did not start telling the boxes of them on store shelves for a long while.
By even age 13 or so, the even average kid knew a lot about "real life". This gave players in a game a huge amount of "real life" back ground to draw upon. A player HAD trapped rabbits, downed a buck with a bow and arrow, skinned that buck, preserved the meat and cooked some of that meat over an open fire. So they would understand concepts like often "a cooking fire gives off lots of smoke", for example.
But with that huge wildly different life experiences also came a lot of....not so bright people. They would "swear" they did or did not do something....or that something was "so easy" or "so hard". Though often they would leave out or forget details...or worse not understand what they saw.
And THIS is what started tons of endless arguments. A player would say it is "so easy" to just grab some soaking wet wood, make a spark with a rock and have a massive roaring fire made in less then a minute. And while maybe not "impossible" (with like dry wood and gasoline), the story is not too likely.
The modern player...born in the last 20 years or so....lives in a much different world. Simple push button technology everywhere. Cheap goods are everywhere....Dollar Generals are everywhere. And Microwaves. And the internet. I grew up in a house with no running city water, no city sewer and no gas line (though we had both a gas and water tank) but had electricity and a phone (land) line. And, some places in 2023 are still a lot like that. But less every year. My "old house" is connected to everything today, right up to blazing fast 5G wifi.
So a typical modern player has no back ground to build on....they have never gone fishing, climbed a rocky cliff or made much of anything. But then too, 5E asks nothing from the players. Or the DM, for that matter. Need a character to swim, eh, just roll a easy check......
You have posted similar sentiments many times, so I don't think I am going to be able to argue you out of your "kids these days..." perspective. I will point out that your growing up experience was very unusual for most people of my generation, and I'm 55. I grew up in a working class town (Nanaimo, BC) and my dad was a truck driver, so we're not talking silver spoon.
But one thing that I think is a problem is that your stance is extremely judgmental. Rather than acknowledging that your experience was different than most modern kids (or, let's face it, adults) and that's okay, you continually posit that your perspective, values, etc. are objectively better. If you don't think "kids these days" are learning "a ton of stuff," as well, then you have another think coming. And just because it is different stuff than your highly unusual (in 2023) experiences doesn't make it inferior.
I've been a teacher for decades. My perspective on "kids these days" is that they work far harder at school than me and my friends did. They are very likely to have part-time job while in school, and most young folks these days don't just work one job, they have a side hustle or three on the go as well. They're growing up into a world where they have to be extremely flexible, so they are constantly trying new things. In terms of values, I see pros and cons. They tend to be more moralistic than my generation was, and I find them more prone to self-righteousness (though that's probably always how older people see the whippersnappers). They are also much more stressed out, but then they are confronting a world that is a lot worse off in many ways than the one I grew up into (the environment, housing costs, etc.).
Here are some objective facts about "kids these days" compared to kids in the 70s and 80s:
1. They are much less likely to drink, smoke, or do drugs.
2. They are much less likely to get/get someone pregnant.
3. They are much less likely to commit a violent crime.
4. They are more likely to attend college.
5. They are employed in similar numbers, and their real wages have scarcely budged.
There are downsides, too - they are more likely to suffer from a stress-related disorder, live at home (c.f. housing crisis), be obese. But by most measures, they are working harder and behaving better than we were at their age. I think they're pretty great, overall.
And what were definitive films of the Boomers and Generation X? Easy Rider? Slackers? Older folks despaired of us, too, back in the day, lest we forget. Now it's our turn to complain about the young 'uns. But the kids are alright - give them a chance.
Oh, and as far as D&D goes: in my day playing D&D was fraught with peril and you were likely to be bullied about it. Today's kids have embraced the game, and even the ones who are completely disinterested don't judge others for playing it.