We probably all think (if it weren't a point of contention in this thread) that most group rides are motivated by a few guys who like to hammer, and a lot of people who want to keep up .... all of whom put a premium on their ability to "suffer." "Sufferfest" is not a word invented by slow riders.
Not saying Every group is "out for blood," but on almost every group ride I have ever been on, even the "Recovery Ride" or "New Rider" rides ... the fast guys got bored and the competitive guys chased.
And while a lot of cyclist like to go slow and at least glimpse the roses ... a lot of riders see riding as highly competitive, and judge the quality of the ride by how long they were able to ride so hard every moment was incredibly unpleasant. There is a huge group of ridders---we all know it--who really do value painful riding.
That is fine, too. If they see the bike as a tool for testing their ability to exert themselves to ever higher limits, ... nothing wrong with that. Some people walk, some jog, some run, some race. Some people do a morning warm-up/tune-up with three-pound dumbbells, some try to maintain a pretty good level of muscle but not bulk up, some try to get stronger and stronger, and some go for max effort--and some are actually into body-building. All good.
I don't do many group rides because it is hard to find a group that feels like I do on any given day. Not the the group's fault, not my fault, nobody's fault. I do what I do, I accept that others can do the same.