80 characters is roughly what a brain can read and comprehend both the start and end of the line. If you're blessed with really big monitors, 80 characters means you can have several files open side by side without wrapping - as a developer, nothing I write is in isolation, the more context I can have visible on screen at one time is beneficial.
One thing I've noticed on projects with no line length limits is more complex code - longer lines allow more levels of indentation before a developer is prompted "hey, this is a bit too long now, maybe refactor?".
A lot of my development is in Python, and there is a good trend to use psf/black to format your code automatically. It removes almost every single tedious discussion about code style, and everything looks the same. It has chosen a default max line length of 88; its not clear whether this was accidental or deliberate, but 88 is a white supremacist "hidden number", so I either change it to 80 or 90, depending on whether people argue for longer lines or not :)
I notice Linus is not also suggesting a change in git commit message format from 50 chars for title, 72 for comments, both of which are derived from 80 character terminals.
Biting the hand that feeds IT
