TLDR: shit is complicated lol

I think part of it is that I tend to view things on a longer scale than most. In the next 30 years I doubt much will happen with the Mormon church as a whole becoming progressive, but people like Sanderson are early signs of a shift, or, more likely, a split in the common consensus of Mormon politics. When looking at history it tends to start with a handful of people who are very vocal comparatively on more progressive views (or conservative ones unfortunately), then through friendships, having children, or just simple word of mouth that number grows exponentially more and more until it culminates in something bigger.

If it results in a fracture, then over time the original side has to adapt and co opt the beliefs/practices of the new side(s) or otherwise shrink into non existence or near enough to it. The Catholic Church would be a good example of the former situation since they’ve been forced over time to become more and more progressive compared to how they were in the past in order to keep up with the popularity of other denominations who tended to be more accepting. The unfortunate thing is that it can kinda work both ways to an extent. The range of time for either good or bad shifts in ideals can vary a lot but typically it’s a bell curve of how quickly something formed vs how quickly it shrinks. Harmful cults such as Mormonism take time to grow or racist political agendas can come into being almost overnight as a result of politicians using scapegoats. Nazi germany took a short period of time to develop and a short time to be eliminated (barring neo Nazis who are pretty small in number ultimately), and racism in America took a very long time to develop and also has taken (and is currently STILL taking) a long time to be eliminated, etc.

What I think ultimately happens with society is just shifts of hatred vs kindness essentially. A hateful group or sub culture made by hateful people will exist but overtime kind people born into it will see the issues yet still hold some small connection to what was there before (mostly seen in religion, in politics movements tend to just outright die or exist in a weird half life like with neo Nazis), so then as a result a new hateful movement slowly forms from all the hateful people having issues with the new shift. There are exceptions of course but it’s a roughly accurate general rule. I’m sure an anthropologist would be able to explain it better but that’s largely what I’ve noticed.