I disagree with this totally. Leg extension and pec deck are both fantastic exercises.
Leg extensions can be great to warm up my knees and quads. They are also good to pre-exhaust before squats. Also, after sqauts, I can use leg extensions to really concentrate to feel fibers that I dont feel during squat. For instance, i feel the lower part of my quads during squats, but i can really feel the upper parts of my quad fire during leg extensions. Plus, i feel that i have some control over what gets emphasized with the way i point my toes. Plus, i can do partial reps at different angles to work any kind of weekness.
And pec deck, i can't imagine not liking it. I get the most tremendous burn from it and my pump is out of this world. Its one of my favorite chest movements. And, my strength in it has gone up very fast!
Maybe i am just a freak or something, but these exercises shoudl not be overlooked.
-Fatty