I am highlighting what I think is the fundamental flaw in your logic.
A number of people are reporting going to WDW at what they think of as traditionally uncrowded times (like mid-October) and finding them to be more crowded than they expected. So, they jump to the conclusion that it's the existence of FP+ that is causing these greater crowds.
In fact, I think it's your next sentence that gets at the real reason why the parks are more crowded more often these days. Disney has done much more to draw visitors to the resort during the slower periods. Things like free dining, room discounts, special events (marathons, etc.) help to increase occupancy in those rooms. You can call those "bribes" if you want, but to me it is smart business. And, more people in the rooms is inevitably going to lead to more people in the parks and longer lines at the most popular attractions, whether you have FP+ or not.
The mantra of the FP+ haters that tiering of attractions at Epcot and DHS means that they can only do one major attraction without waiting an hour or more in line is, frankly, a dramatic misstatement of the truth. There have been several reports in recent weeks of people encountering short lines at the parks, and that is with FP+ being used at all of the resorts. So, there are still plenty of off peak times.
But, even with a larger crowd, all you have to do to enjoy the two major attractions at Epcot and the 3 major attractions at DHS is to get to the park at or around opening, go immediately to the attraction for which you don't have a FP+ reservation, and ride it before the standby line builds up. If you get there early enough, you can probably do more than one of the headliners with short lines and still have your FP+ reservations for later use. Two weeks ago, we arrived at DHS before the actual 8:45 opening and rode TSMM, TOT, and RNRC (using single rider) without using a FP and were done with all 3 by 9:40. So, don't tell me that it can't be done.
And, of course, it will be more difficult to do that, during the busy holiday times, but that has ALWAYS been true. I can already see the people next week who will look at the wait times on the days around Thanksgiving and blame it all on FP+, as if touring on those days would have been a "walk in the park" otherwise.