There’s a fine line to walk between letting folks off too easy and making it even worse by going scorched earth on them.
If they were treated as enemy combatants with their rights as citizens revoked, then you are likely to inspire more anger and righteousness than fear.
The mindset of those that are receptive to the position of the insurrectionists is that government is undemocratic, corrupt, and authorian against them. It deflates their position when those folks get due process and frequently get off with light sentences. Incidentally, a lot of the key people got 4 to 18 years in prison, hardly a slap on the wrist.
Lots of precedent where any initial offense is forgotten in the wake of an oppressive response. The best results have been where the “victor” exhibits a reasonable response rather than trying to go all in, especially when you are dealing with millions of folks roughly on the side of the guilty.