Are there reasons for not storing boolean values in SQL as bit data types?

Question

Are there reasons for not storing boolean values in SQL as bit data types without NULL? I see them often stored as integers without constraints to limit values to 0 and 1,

Answer 1

I think third normalization form would state that you should have a table that stores the values True and False, and reference that. Make sure you do that with your dates as well!

But who completely adheres to 3NF anyway? ;)