Because starting the year after the Eagles won the Super Bowl helps make his argument better.
Honestly though the fact that the Eagles were able to, in that timeline, win a Super Bowl, blow up the team, build a new won, and make it to the Super Bowl with that team, all in that short of a timespan (when the Cowboys have not made a conference championship game in 29 years) sort of shows how quickly a well run organization can completely rebuild. I am just sort of in awe that of all the teams to argue the Cowboys against over the past 29 years, the Eagles are the team being picked when I would think they are overall a top 5 team in accomplishments during that time (this one I would have to fact check to confirm though).