Low contrast is a bad way to reduce distractions though, because it disproportionately affects users with vision impairment. What is “subdued” to a user with normal vision becomes illegible or even invisible with mild to moderate vision impairment. I have to wave my mouse all over the screen on the default theme just to find the buttons
Besides that, “greyed out” in user interfaces has traditionally meant, “this is where this thing would normally be but you can’t do that right now”. There’s something to be said for familiarity and consistency between applications.