Err, as an Atari 400/800 owner, I can assure you that they did in fact have an overscan problem. Atari BASIC even defaulted to not printing to the first 2 characters and last 2 characters of each line.

Here's an example Atari BASIC program that uses POKE statements to change and then restore the default margins.

https://www.atariarchives.org/c2bag/page003.php