Performance, mostly. If you have to re-parse part of the code many times a second, in a text editor. For [pseudo]structural editing or syntax highlighting, for example.
Optimizing for your edge case would require everyone writing and reading code to conform to this extra thing, which seems completely unnecessary. Machines are pretty fast.
Performance, mostly. If you have to re-parse part of the code many times a second, in a text editor. For [pseudo]structural editing or syntax highlighting, for example.