In the era that python was created in, autoformatters were not a thing and I appreciated the forced indentation. Nowadays with autoformatters being standard, the downsides of semantic white space is not worth it.
It makes scope visual and consistent. IMO it's less dumb than having scope defined by pairs of curly braces which are impossible to read without indentation and require extra effort to keep matched - unless you try to automate the matching with a good IDE.