I started playing D&D with OD&D and then Holmes Basic, and then AD&D1e when the DMG came out. My experience then (as now) is that AD&D1e is needlessly complex and arcane with the rules as presented (initiative segments, weapon vs AC tables, initiative segments, weapon speed & reach, initiative segments, ability scores that basically do nothing unless you have a 16+ [17 Strength = +1/+1?], initiative segments, species, age & gender ability score adjustments, initiative segments, huge spell lists, initiative segments, minutia for determining if characters have contracted diseases or parasites from adventuring, initiative segments, etc).
When B/X was released in 1981, it was a HUGE breath of fresh air for me, and I haven't stopped playing it since. I play other editions (I'm in a 5e and an AD&D1e game right now), but B/X is where my heart is with simple unified ability score modifiers, no ability score adjustments, 12 spells per level for Magic Users and 8 for Clerics, and a super-simple but robust framework to hang all your house rules from.
Also, Conan is a Thief in B/X. A thief with ridiculous ability scores, but definitely a thief.
B/X isn't just the "current" focus of the OSR, it generally has been the focus through the whole thing.