Bingo. It's a completely different approach.
In 5e, you build the character by choice. The primary power of characters is through abilities; this is why, for example, people can "map out" characters and character builds far in advance.
AD&D wasn't like that. There was an element of serendipity- a lot of your "power" and "ability" came from magic items you acquired. So a lot of your core identity, even including weapon choice, would be changed by those items that you found.
This began to change, first with the advent of weapon specialization.
Begins tugging at beard and drinking mead ... and it was all downhill from there!