Most web developers are probably not particularly concerned about how fast their code is in relative terms. There’s a huge amount of room for UI library benchmark competitions that all lie easily within “good enough for the user.”

It’s also important to note that the virtual DOM isn’t just (or perhaps even primarily) about performance. It’s also about maintaining DOM state across updates, like focus, cursors in text inputs, etc. Modern browsers on modern devices are fast enough that for many web apps you probably actually could just document.write the entire DOM from scratch on every component state update if you didn’t care about that DOM state.