IMHO another reason to not lie is that it further erodes the character of the lier. Lying gets easier with practice. The self-discipline of facing consequences rather than dodging them weakens. Justified guilt accumulates and weighs down the pyche, at least for some people. It gets harder to trust others, as it become more normal to assume they are lying to you.
Why wouldn't it? The people who care about a resume gap is HR, and the people you work with are not those people. The daily people you work with don't care what your past is, it's only HR that has a negative opinion of job gaps on hire-ability.