i agree with you in principle, but i am not sure that this is simply a technical limitation. it feels to me more than just a preference. i can't explain it, but looking at the apple systems font example in this article: https://storck.io/posts/proportional-programming-code-fonts/ i find it much harder to parse (visually scanning the structure) than the monospace one below. perhaps it is simply what i am used to. but i feel like i am having a more violent reaction than i should have if mere preference and habit were the issue.

perhaps the issue is the specific choice of fonts. the author in that article exclaims that if you allow proportional fonts then any font can be a programming font, while the author of the following post claims otherwise and set out to make their own proportional font that is suitable: https://timgord.com/2024-01/lisnoti-a-proportional-font-that... . there are other such projects like https://input.djr.com/info/ and https://go.dev/blog/go-fonts

one issue is that of distinguishing similar characters, which the above projects try to address while some people claim it's not an issue at all: https://alexkutas.com/posts/non-monospace-font

there is also the issue of alignment mentioned in the first article, that could possibly be addressed by limiting character widths to multiples of the smallest width.

but there is still the issue of interacting with other programmers, mentioned in this article: https://nelsonslog.wordpress.com/2021/09/12/proportional-fon... we would all have to agree on the same font if there is any kind of alignment needed apart from indentation. right now we can say that you can choose any monospace font, and things will look as intended, but with a proportional font things will look different depending on the font choice. whether that is an issue or not needs further study i think.

more discussion of pros and cons can be found here: https://stackoverflow.com/questions/218623/why-use-monospace...