There are remnants of that era left in certain airports under the guise of "slot restrictions"...giving airlines control of the terminal gates and limiting access to new entrants. O'Hare and LaGuardia are 2 such airports.
No I'm not a pup. It has nothing to do with the number of carriers...it has everything to do with route competition...which is drastically higher now.
[link|http://www.econlib.org/library/Enc/AirlineDeregulation.html|For example, between 1979 and 1988 American Airlines increased the number of domestic airports it served from 50 to 173, and United Airlines from 80 to 169, both without major benefit of mergers. As of February 1992 a traveler between Boston and Phoenix could choose among six airlines; in 1977 there were only two. Again, back in 1979 only 27 percent of all passengers traveled on routes served by three or more competitors; by 1988 more than 55 percent enjoyed that kind of choice.]