Nope, wrong again. If you take two pitchers with the exact same mechanics. Exactly the same. Same size, weight etc. The stronger one will throw harder. This is true with basically anything - sprinting, jumping, etc.
Now, mechanics are certainly important, but without strength it makes no difference. You can have the best mechanics in the world, but if you are a 95 pound weakling you will never throw 90+. There are plenty of strong guys with crappy mechanics that can throw in the 90's though. My stance would be to work on both, they do not interfere with one another. I can strength train three times a week and still have plenty of time to do skill work in a sport. In fact, every pro athlete is doing this.
P.S. Show me this post with a person losing velocity from strength training.