Actually, first edition did use combat tables--and I LOVED them! Dig out your old 1E DMG and check pages 74 and 75 (page numbers that I still remember even though I haven't used them since 1989).

You could still employ the THAC0 concept to an extent--though at some point the number needed to hit went below zero, and the number to hit never went above 20, so there were some differences. Still, because of the layout, until somebody pointed that out that the numbers could be used as a THAC0 (which occurred around 2E for most of my friends), it looked like you needed to use those puppies if you were going to play AD&D!

Before 2E came out, I never heard anyone say, "It's simple, just calculate what you need to hit AC 0 and then subtract what you rolled."

It was always, "Find out what you need to hit the monster's Armor Class using the DMG. Then roll the die and add in all your modifiers, like Strength, Weapon Specialization, and Magic. If the modified number is higher than the number on the table, then you hit!" Everyone I knew played it that way until 2E came out, and that included the few conventions that I attended.