I have an interesting idea for a TS3 world, but it would require me to get rid of all story progression in that particular instance of TS3. No EA story progression, no modded story progression. Is there any way to do that? I heard somewhere that simply turning off the EA story progression does absolutely nothing; is that true? I'm confused.

The way I would try to do it is use Twallan's Story Progression and change all the settings so absolutely nothing happens. I think that would work.

If you turn off Story Progression, Story Progression is off. I don't know what they mean who told you that it is otherwise. There are, however, some mechanisms in the game that some people think are part of Story Progression but which actually are not and are independent of it. Co-workers will be chosen randomly or created afresh if an active Sim works in a rabbithole or a profession like firefighter that requires co-workers; some roles like Stylist or Consignment Clerk are filled with residents, if there are none the game will move some in; the Neighbourhood Pet Adoption system is not part of Story Progression either. Story Progression also has nothing to do with inactive Sims leaving their houses and visiting their neighbours or community lots; this is done by MetaAutonomy and I don't know whether NRaas SP can disable that. And turning off Autonomy is only valid for the active household.

When TS3 came out the story progression tab on/off didn't work. It was always on. But it was fixed with the first patch.

Pet adoption can be turned off with overwatch. If you have awesome the game will not generate co-workers for RH jobs unless you use the tuning to hang out with them while at work. At least I think this was from awesome.

Thank you for your responses! Now I know what I'm going to do.