Back then you'd have to do a specific build to get 100% critical chance but it'd leave only boots left, and marksmen benefited most from doing so; dodge however could be used by anyone even though it would at most be 30~40%. There was an item called 'sword of the divine' which had the passive effect of making your auto-attacks unavoidable, however neither riot nor more knowledgeable players educated common-folk about it, and most new players didn't explore the item list to find out themselves. But this item was removed when riot striped the dodge stat from the game (along with runes back when they were separate from masteries), due to common complaints of being unable to deal damage. It returned later after being reworked; giving some attack speed, that when activated, would loose the attack speed to make the next few auto-attacks guaranteed critical hits . . . only to be deleted again because it was often ignored or straight-up outpaced by other items.
Fast forward to season six when they updated marksmen, and the buffs to their items made it possible to reach 100% critical chance with only four items that could be interchanged with a few options, and have an extra slot for whatever they want besides boots.
Yeah damage creep isn't only buffing damage, and can include nerfed defense.