I'm not a computer scientist so I can't rule whether function scope was a mistake, and can't see how block scoping would be considered too complicated, I personally think it fits much better with my mental model. Then again, Python doesn't have blocks in the traditional sense of the word IIRC, in C style languages the accolades are a pretty clear delineator.
Parts of my previous job were terrible because it had JS functions thousands of lines of code long where variables were constantly reused (and often had to be unset before another block of code). That said, that wasn't the fault of function scope per se, but of a bad but very productive developer.
TBF you can have block scoping in an indentation-based language, though it probably help to merge the too, as in Haskell: `let…in` will define variables in the `let` clause, and those variables are only accessible in the `in` clause (similarly case…of)
Parts of my previous job were terrible because it had JS functions thousands of lines of code long where variables were constantly reused (and often had to be unset before another block of code). That said, that wasn't the fault of function scope per se, but of a bad but very productive developer.