When 2016 election was won by Trump, it was at most a minority viewpoint that the election was rigged - in fact I've never heard of it said. Trump lost the 2020 election, and it was presupposed that the election will be rigged, leading to violent protests in complaint of the election result.

The real problem is that there's an epistemic crisis whereby people have lost trust in long-lived and functioning institutions, and that has been fuelled by conspiracy theorists, some of which have been given credence by the sitting president (e.g., Alex Jones).