They are claiming the exact opposite of that: not having root access isn't a limit on creativity.
They're replying to a comment arguing for open devices. Saying "I'm fine with a closed device" is at best irrelevant. "I'm fine with a locked-down computer" is no argument against "I want my computer to be more open", as, in the end, if you're fine with your locked-down computer, just keep it locked down.