This. 6' of distance between parties means longer lines, but not necessarily longer time waiting: those are two distinctly different things, but a lot of folks don't seem to be separating them. I've heard so many friends talk about how "crowded" the parks are because they saw a line stretching far longer than usual - but they totally missed the fact that it was continually moving and was all of a 15-minute wait. And there's also the fact that on continuous loaders, like HM for example, 6' between parties means not being able to efficiently load every ride vehicle - that means rides operating at reduced capacity, which further extends lines and may increase wait times. And then you also have attractions not operating at peak efficiency because that requires more labor, which WDW is trying to reduce to save on costs: if only one side of Space is running, that reduces the number of Guests who can ride per hour.
I've been visiting the WDW parks since the late 70s and regularly for 3 decades now, so I've pretty much seen it all: from the emptiest of empty days, to the most crowded of holidays, from ride tickets to all-day passes and no FP, to OG FP to FP+, and everything in between. The group psychology of theme park visitors is endlessly fascinating! In the days before FP, hour-long waits for rides was common - that was why FP was met with such enthusiasm! On a very slow day in the Olden Days, I'd ride every ride with no real wait and backtrack to do some rides multiple times, but on busy days, I might only experience half the attractions. My first times riding Space and Splash involved 3-hour waits in line. That's just the way it was and if we wanted to ride something, we dealt with the wait. FP reduced wait times, making it easier to do more in less time. FP+ continued that trend. It seems to me we now have a big group of WDW visitors who have never known life before FP and their expectations (created by Disney, to be clear) are entirely at odds with how a park works without FP. I completely understand why to many of them, the current situation feels too busy, too crowded, too little value for the output of time and money. For me, it's full circle: it's 1995 again and if I want to visit on a busier day, I know I'll have to choose between waiting a while or skipping some rides, or I can opt for a slower day and wait less, do more.