This would explain why that 8-bit arcade font (it's in numerous Namco and Atari games) that's everywhere in 70's and 80's arcade games was everywhere.
[0]: https://www.amazon.co.uk/Arcade-Game-Typography-Pixel-Type/d...
Also if you look at all the ways letters and numbers have been drawn in C-64, NES, Genesis, and SNES games; there's lots of room for creativity and design even in an 8x8 space.
If you made a vertical line only one pixel wide, on many televisions like the Panasonic I used it would be nearly impossible to see.
And while color monitors of the day were an improvement, they still weren't what we would consider acceptable today. I eventually upgraded to a Commodore CM-141, and single pixel vertical lines still weren't great.