My experience is back when I started (86), was styles and groups were all over the map. There was no internet in the sense we have today (watching someone use the internet was like watching alchemy to me when I first encountered it) so the only things that unified style were rulebooks, magazines, and experiences people had at conventions or game stores. There was also word of mouth. But you could go from group to group in the same town and find wildly different styles (I think in closed communities like high schools and colleges you often found more shared styles in clusters of groups, but those still varied a lot by individual GM). I will say, there seemed to be way more dungeons in the 80s to me, and way less in the 90s. But D&D was also far from the only game in town. I recall other gaming options being more viable and widespread than today (though I would say there also do seem to be a greater volume of different RPGs now due to things like POD and desktop publishing). I will say: very different gaming landscape than today.