Is there anything significantly different about monster power or lethality between B/X and OD&D?

The main thing I am trying to figure out is why in B/X and onward, basic D&D doesn't allow fighters multiple attacks against 1hd monsters. Is it really just for simplification's sake? If so, that's a massive downgrade for fighters.

>>95909005
>stir drama
should read
>stirring drama
I can't brain today.