It's like saying you're convinced people reporting they feel more productive in a mauve-coloured room are liars, or those that drive automatic vs manual. Maybe they just find muave a restful colour?
What the hell are you talking about?
It's not to say an IDE isn't a useful thing, they just have their place like anything else. I personally find autocompletion useful for a couple of weeks going into a new language or project after which it's very often more a distraction than a productivity enhancer. Same goes with e.g. Git integration. I wouldn't presume to say a Git integration user simply needs to learn Git in much the same way I wouldn't expect someone to tell me that I can't use Git just because I don't use the IDE Git integration. They're just tools
As long as you don't have some kind of stochastic or >5s impediment taking you out of a state of flow, most developers' productivity is going be vastly more influenced by their knowledge, understanding, and ability to focus on the problem they are working on than the marginal difference in time it requires to perform some navigation or editing task. Which is not to say that vim is bad or that you shouldn't use it, but that it's just a text editor and if you get triggered by someone not liking it or thinking it's more trouble than it's worth, it might be worth taking a step back and thinking about why it's something that triggers an emotional/defensive response, rather than the kind of reaction you'd have to someone liking strawberry more than vanilla.
This is the exact same sweeping inferential leap as the original comment. I happen to think people who drive red cars do so only because they want to incite a sense of danger and potency in their road opponents, people who wear boots obviously want to identify with Ukranians on the front lines and any claims it helps with their flat feet are obvious rubbish.
Tooling and language obsession is boring and borderline offensive to anyone who has been around for a few years. Imagine walking into someone's workplace and demanding they replace their well worn chair, would you do it? Imagine insisting someone use vim because their IDE didn't have a natural pipe-through-shell-command function.