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When someone says "back then we all played like this" it's rubbish. Back then we all played differently.
In the early 80s: there were differences in style, and different house rules, and differences in our preferences - all of which changed the output when we played... 100% agreed on that.
However, we almost all shared the same inputs. We all used the same starting blocks. There wasn't a huge spectrum of different RPG games and editions to compare. Most of us learned under the same evolutions of rule sets. We didn't have a kajillion 3rd party resources. We didn't have the benefit of the internet off of which to bounce questions.
The tools of construction for all early 80s D&D players were primarily the basic set/expert sets, the original AD&D books and a bit of Dragon Magazine. They introduced a few monster books (MM II, FF), then expanded the rules with UA, Companion/Master/Immortal, OA, etc... but for the most part our experiences all began the same:
Get the book.
Read the book.
Be confused by the non-intuitive layout and poor explanations.
Fumble through a few games.
Try to 'fix' the problems we encountered (some of which were flaws in the game, some were misunderstandings of the rules) as we went.
That experience shaped how we approached the game. It has continued to evolve over the next 35 years, but it is the foundation upon which our houses are built. Those that learned in the 90s (2E), early 00s (3E), etc... have different foundations. What is built upon that myriad of foundations is different, even within a 'generation', but the foundations tend to be similar during an era.
It is like we all went to the same (remote) university and then went out and did different jobs in the same sector. There is a reason people think back on their university experiences as the greatest years of their lives, and some of that really applies to learning D&D in that era.