testing inequality with columns that can be null

Question

So, I asked a question this morning, which I did not phrase correctly, so I got a lot of responses as to why NULL compared to anything will give NULL/FALSE.

My actual q

Answer 1

If

where ((A=B) OR (A IS NULL AND B IS NULL))

is for equality, then why just not use:

where NOT (
  ((A=B) OR (A IS NULL AND B IS NULL))
)

for inequality?