It's not that inaccurate. It's in the right ballpark, just glossing over all of the details of what that means in practice. Would you prefer "The virtual DOM helps make React work a lot faster than doing direct manipulation of the DOM using vanilla Javascript"? Doesn't really seem like it makes that much difference – and the author links to an external video that explains it all in more detail.
Anyway, any senior developer who laughs at a less experienced one for repeating that kind of thing is a bad developer. I'd like to think they'd take the time to correct the inaccuracy :)
> Would you prefer "The virtual DOM helps make React work a lot faster than doing direct manipulation of the DOM using vanilla Javascript"?
I am not sure this is even correct. Firstly, the famous js framework benchmarks (https://github.com/krausest/js-framework-benchmark) based on adding/removing list items used to have vanilla JS as an unbeatable winner, despite its direct manipulation of the DOM, and React was definitely significantly behind. Secondly, as the README for morphdom says, the real DOM is very fast (https://github.com/patrick-steele-idem/morphdom). If I remember correctly, virtual DOM was supposed to solve the particular performance problem where you would otherwise just throw huge chunks of DOM away rerendering them anew every time your app state changed. But this is a very special (although brilliant) approach to keeping your UI in sync with your app state; you wouldn't necessarily do so if you wrote your app with vanilla JS.
Oh, I am sorry, I re-read your sentence, and I think I misunderstood it. Yes, if React were using real DOM rather than virtual DOM it would have been slower, but the author was not trying to make _that_ point.
Anyway, any senior developer who laughs at a less experienced one for repeating that kind of thing is a bad developer. I'd like to think they'd take the time to correct the inaccuracy :)