Semantic whitespace is awful because whitespace (something that you can't actually see) has meaning in how the program runs. Braces {} for scopes gives you the ability to easily tell at a glance where a scope ends. Whitespace doesn't allow for that. Especially, especially when you can accidentally exit a scope (two new lines in a row with Python) and it's not actually an error (Pythons global scope). Yeah formatters and linters make this less of an issue but it sucks... Languages with legible symbols for scoping are significantly easier to reason about, see end symbols in Lua.