Exactly. The vast majority of matches are there to be won. Much as I want to see my club, Blackburn Rovers, have a successful season and get promoted I know in my head that would mean all of next season watching lambs to the slaughter. What good would it do us? With luck wipe out our debt in one season before we got relegated.
Not much of an ambition really. Get promoted. Wipe out the debt. Get relegated. That is not what football is all about.
It is what football has always been about (except possibly the debt bit) for certain teams. There have always been "yo-yo" teams who regularly get promoted then relegated. It has always been the case that the teams promoted to the top division were the most likely ones to be relegated the following season.
I also disagree about your assertion "never before to the extent 5-6 clubs totally dominate the game with no serious prospect of that dominance being broken." There have been such periods, sometimes with only 3-4 clubs dominating. But that dominance has always eventually broken, other clubs have joined the big players, while some have fallen away.
Even now, you listed Newcastle in your list of dominant clubs above, but they were relegated in 2016, and struggled for several years after returning to the PL. Even last season, they failed to win any of their first 14 games, until Howe was brought in.