Marx, most mo rabbis don’t tell people to do most of the aveiros that they do. Also, more importantly, the eruv supporters aren’t telling them that you can carry on shabbos, rather they’re saying there’s an eruv, an established halachik device. When some mo rabbis say that girls should be taught gemara, or that filters aren’t necessary, or that negiah isn’t a big deal, they’re telling their constituents something that is availably disprovable. I agree that the level of culpability is reduced when they’re following a rabbi, but at what point do we say that they’re expected to reject them? It’s a good question which i don’t have an answer to, but it probably boils down to a case by case, personal cheshbon.
With the eruv, there were rabbonim who learned the sugya differently than rav moshe, while the circumstances of the eruv were quite… Political, but that’s besides the point
If someone is a product of day school, can barely read let alone translate a sefer, and their rabbis led them to believe XYZ halacha simply doesn’t exist, are they like a tinok shenishba in those matters? Or maybe not, because they do know that there are “fanatics” who keep much more than they do, and they’re not like conservative who are taught openly that halacha changed, rather their belief system is that halacha must be kept… So are they held accountable in shomayim for not investigating themselves? Again i think it’s personal.