For someone paranoid about correctness, that's 1% of lingering doubt about every single operation in the IDE.

The 99% stat is quite likely a big exaggeration.

Refactoring is far far harder to do reliably, and more straining as so much more responsibility on the programmer.

IME, add that 1% to another "1% isn't worth switching" argument with some other Python deficiency and then to another and so on, and reasonable case for choosing other languages can be made. I'm not saying Python should be abandoned for all projects, but we should be careful with "but if we make everyone use this one tool, and this one tool does it right almost all of the time, so we're good" arguments.

I'm reading Type-Driven Development with Idris right now exactly because I don't think Python is always the correct choice. I just don't find slight improvements in IDE features to be relevant.

What about the time accounted for in each of those buckets? If "that 1%" accounts for more than 1% of debugging, error chasing, and related time it starts to look more important, yes?