The first thing that comes to my mind is, eccentric work is very tough on the body. Not only on the joints and tendons, but on the muscles as well. You body/muscles need to have a certain amount of total time under tension to grow. If you try to achieve enough volume by eccentrics alone, you will eventually crap out, either due to injury or just feeling like shit from the muscle damage, thus impeding your ability to grow.
Let me tell you, eccentric loading places a LOT of stress (forces) and strain (deformation) on the muscles, whereby if you do it enough too often, you will eventually lose strength and lose muscle by not being able to train properly.