Note that when we talk about line length limits, we're actually conflating two separate concepts: 1) The maximum width of our viewports 2) How long we want ou

Note that when we talk about line length limits, we're actually conflating two separate concepts: 1) The maximum width of our viewports 2) How long we want our lines to be WRT the second concept, the general rule of typography is that a line should be 60-80 characters long. But, crucially, this is not counting indentation; a "line" here begins at the start of the text, not at the start of the margin. In the modern day we could decouple these two concepts. Imagine a standard code format that assumed a maximum viewport of, say, 120 characters, but still wrapped lines when they reached 80 characters in length, not counting indentation. Then you could get the benefits of both enforcing a maximum viewport size while having a comfortable line length for reading.