I started playing in '83 with Red Box DnD from the BXCM line of sets. My initial introduction was through a friend who saw me reading one of the 'Fighting Fantasy' game books and told me about DnD. He played with his older brothers and sister IIRC.
The only modules we ever played were the ones which came with the box sets, and only the first of those was a plain dungeon adventure. Yet we definitely played mega dungeons. We used to build
huge dungeons filled with monsters, traps and puzzles. I distinctly remember building and playing 20+ level dungeons. One of them was set inside a giant statue.
I never played Rogue (until later when I played Angband) and I hardly ever read Dragon, though I might have read quite a few issues of White Dwarf back when it was a 'proper' magazine. I didn't really know anyone who played and wasn't part of my group, plus I was the main DM for us. So something in the BXCM books must have made me focus on dungeons.
I think it was probably a two pronged phenomena. Firstly, you start with dungeons, and as the PCs level up you just build ever bigger dungeons to challenge them. If you enjoy that aspect of the game (and we did, we were only in our early teens) then you stick with it. Secondly, dungeons are easy to build. You can spend hours planning them in advance and the players have a very difficult time subverting your adventure (and we were very adversarial at the time, as I say, we were young

).
When I went to college I met a new crowd of players and got in to a much wider range of campaign types.
Cheers,
Dan