I loved this episode of The Megadungeon #podcast, Interview with Che Webster. https://themegadungeon.com/the-megadungeon-episode-3-interview-with-che-webster/
They talk about Caverns of Thracia (which also ran a few years ago ago, using D&D 3.5 at the time), but in the intro they talk about the benefits of B/X: Basic and Expert D&D from the early eighties! Character creation is fast, combat is fast, the rules are simple. That’s why my Halberds & Helmets is basically a house ruled variant of it (via Labyrinth Lord).