I really can't agree with that.
Back in the day, you had an amateur tour on which people competed. I think we can safely assume that an amateur tour in those years wasn't very deep, because few people could dedicate themselves to tennis, as it didn't bring incomes to them. It is thus very likely that there was a big gap and the few players who were either/both more dedicated or had more talent and the others. Those players would dominate the amateur tour. Then, a business man like Kramer would offer them a contract to become a pro player, and the guy would then become one of the very few pro players. In order to become a pro, he only had to dominate on the amateur tour, a tour where the average level of play might have been very low. He would then be considered as a top players, as there would be a lot of advertising on each match, and the fact that they always play each over in small venue increase their hypeness.
Some of them would dominate, but, as nobody can always play at his best level, event the better player would sometimes lose, allowing the lesser players to win titles and grow their name. The lesser player place in the draw was nearly granted, as very few amateur player where pushing to enter the pro tour.
Today, only the cream of the crop turn pro, because the selection process is much more hard, and much more progressive. A player has to win future, then challenger before being able to enter the top 100. There is no big gap of level of play between the different kind of tournaments: There is a continuum between the top players and the lesser one, which is very regular, and which make it harder to make a name to yourself. Beside, I really believe that the level of dedication today of the player is nowhere the level it was in the 50's on the amateur tour, for the obvious reasons I mentioned before.
Now imagine that today, we had a huge gap between the pro tour and the amateur tour. You would have Federer, Nadal, Djokovic, Murray, Roddick, Davydenko, Gonzales, Nalbandian, Tsonga, Blake, playing very often some WTF venue against each over. They would never play against the so called journeyman that are so disrespected in this forum, and thus, Blake, Nalbandian and Gonzales would never show their vulnerability against lesser player. How hype would be the tour in such a situation? How godly would their name sound? Federer and Nadal would dominate. Then Djokovic and Murray. Then nobody in the third tier would dominate, giving the impression that they are all awesome players. And of course, time to time, a tier 3 players would win it all.
If your place at the top is not threatened, then the level of competition might be weak.