Retro-Gaming Enthusiasts Are Getting It All Wrong

It's a bit more nuanced than that; the systems being emulated often didn't even have square pixels. So getting a 4:3 image is going to involve scaling and/or cropping the output.

The best description I know on the complexities of properly emulating the display hardware is this blog post: http://gamasutra.com/blogs/KylePittman/20150420/241442/CRT_S...