It's a good counter-point. A junior full-stack, for me, is a junior that can be effective in all parts of the stack, and takes ownership of the work until it's done. I have one, and every time he doesn't fully grasp something, he asks the most experienced full-stacks within the company on how they would approach the problem, and he openly discusses complex issues with other front-end specialized people. He collaborates effectively. I strongly believe front-end specialists are valuable and needed within every company. I just don't agree that a full-stack team cannot be effective. :)