parity noun
1
: the quality or state of being equal or equivalent
https://www.merriam-webster.com/dictionary/parity
Comparing the number of Super Bowl champions in the pre- and post-era 1993 league collective bargaining agreement is not a reasonable equivalency. The assumption is that the league, a collection of teams (currently totaling 32), is more competitive between more teams on an annual basis. Contrasting any differences between the collective champions for each era with each other is not what the term means for the NFL.
A better, more accurate way of understanding parity is both reviewing how many different teams are consistently vying for playoff appearances from season-to-season. Not just the various combinations of teams making the playoffs each postseason but seemingly appear as viable entries in the latter half of each season.
In the pre-salary cap era, it was a given that a smaller number of certain teams would make the playoffs from season-to-season. The result was a byproduct of stable, mostly static rosters, having sound tenured coaching and sustained by insightful management. A much smaller number of teams assembled a greater overall percentage of the league's player talent and retained their monopoly over longer periods of time.
In contrast, the post-salary cap era ushered in much larger player movement between teams--including a greater quantities of upper echelon talented players. Rosters became more fluid. What sound coaching and insightful management
used to take for granted became an after-thought.
Putting together a smaller core of upper tier players with a workable cast of supporting teammates and a good or better coach, along with good health, became the norm for greater numbers of teams to make runs for postseason appearances. Before that fateful ratified CBA, some fans of certain franchises 'knew' their teams would make the playoffs while many fans felt their teams had no chance of reaching the playoffs before the season began and were very often right.
In the current era of the salary cap, more fans of more franchises 'know' their team might make the playoffs, might make a playoff run, and might reach or even win the Super Bowl. The competitiveness of the league overall became reality in this era. That is the actual definition of parity in today's NFL. And the league has capitalized on engaging many more fans through parity in the form of BILLION$.