I think the OP's point is valid in regard to the whole "Federer could beat you with a frying pan" argument. Of course he couldn't, it's an absurd way to try to make the point that players should worry more about their strokes then their equipment, and as long as you have a serviceable frame you should use it to improve as opposed to trying to improve by buying new equipment. I'm sure Federer could beat 95% of the people he normally would beat with a wal mart racquet, but the other 5% he might not be able to return a serve against.
My own anecdotal point: I played a casual set with a friend who I used to hit around with during summers off from school. I'd usually win but it was competitive.
I started playing tennis all year round and I've been playing in leagues. I'm a 3.5 bordering on 4.0, he's a borderline 3.0 at best at this point. He had a few racquets of his and his wife, including a old copper ace...I played with that one. After attempting a few topspin forehands and having the ball go into the fence because the strings were 15 year old nylon, I just started dinking the ball back. I end up winning 6-3 or 6-4. He had this sort of "I thought you'd be better than that..." kinda response to his loss.
2 weeks later we got together again and I brought my tennis equipment. I beat him 6-0 and he barely won a point except for a few unforced errors on my part. He said after the set that I "look like a pro" from his vantage point. Of course I'm not even close to that good, but the point is: yes equipment does make a difference, it just tends to be exaggerated and obsessed about by some people, especially when it comes to aquiring pros equipment or matching their specs or whatever.
3.5 player. Equipment: Prince NXG OS, hybrid kevlar mains/poly crosses 50 lbs