Pretty much sums up my feelings. I know for a fact that the opinions expressed in the article are not shared by plenty of older, ex-Tour pros. They try to teach their competitve students the modern game. Like Tim posted, not all older rec players are uncoordinated physical wrecks either.I thought the article had a few good points but overall had a lot of inaccuracies.
1. Open stances are good: you can still hit with your body weight going forward to the front foot with an open stance and it lends itself to quick recover and hitting more topspin.
2. A WW follow-thru is certainly not bad if you learn the wrist is passive thru contact and the WW is just the natural finish if you rotate your body and finish with the racket near your opposite stroke. Yes, if you think pros are using wrist manipulations at contact to execute WW finish, you will have an inconsistent stroke and likely hurt your wrist.
3. Roddick, Federer and many others still use arms up together technique on the serve which is good. Modern pros may get the front shoulder higher with the back shoulder down a bit which makes it look like the front shoulder went up first. But, the arms work together in most serves with the front shoulder tilting up and back shoulder down.
4. Even rec players want to eventually learn to use some upward motion on their serves to generate a bit of topspin. Yes, you can hit effective serves with mostly shoulder rotation but you will hit more spin with a bit of push upward into contact. Get the front shoulder up and a bit of leg push up should be the goal of 4.0 and above levels.
I was disappointed in the article. I think the pros hit the way they hit because it is "optimal" technique and is better for the body and provides more effective results. I for one will still use open stances, WW finishes with a passive wrist, and continue to work on hitting up on my serve. I think this saves my body a lot of pain and provides a better way of hitting.
I think even beginners can learn some of these principles if they have a good coach. A good forehand stroke pattern can be learned quite early.
The article was full of misleading assertions as well. For example, he said that all pros hit their forehands with an extended arm. Actually, only two top pros, Fed and Nadal do. The rest have a bent arm at contact.