The main reason for populism is that the incumbent governments do a consistently poor job satisfying their constituents' preferences and interests, so people get desperate to find something / someone different that might work better. Always has been, always will be, social media or not.

Example: https://papers.ssrn.com/sol3/papers.cfm?abstract_id=4230288

We haven't invented a governance structure yet that would be immune to this, although some are better than others. I'm sure the current social media algorithms are harmful as well. You can ban viral algorithms, but the hostile actors whose literal job it is to drive polarization / populism will just find other strategies to effectively deliver their message.

"Education" is nice and all, but millions of people keep smoking despite the obvious harm and decades of education, not to mention the many limitations, taxes, and bans. I mention smoking as an obviously-bad-thing that everyone knows is bad. Education succeeded, and yet, here we are, still puffing poison. But you can also look already-polarized political topics. There's been no shortage of education on those topics either, but if that worked well enough, we wouldn't be decrying populism right now.