-2 is massive in old school D&D; that -2 should have been a -1 at most.
In 3e it was due to how the modifier mattered more than the value, so the -2 to the ability score was effectively -1 to the modifier. It was then that they did away with the "set the ability score X to Y" items and effects in favour of bonuses (+2, +4 and so on) only to go back to the original idea in the end with 5e, even though they kept the modifiers.
