What specific part of my argument are you disagreeing with though? You don't need empirical evidence for what you can derive from definitions. It would be more complex if the question involved time or cost.

I agree with what you're saying in general and I'd love to see some robust studies too but you have to accept here that it's prohibitively impractical to get many multiples of developers/teams to develop the same app over several months through to the maintenance stage with all other variables isolated.

That's why most studies use inexperienced students or are based on crawling GitHub repos, then end up being really flawed.

It would probably be challenging to show autocomplete, syntax highlighting and undo/redo lead to productivity gains as well - nobody has the resources and/or will to investigate these at a large scale with all other variables isolated.