Certainly even the Founding Fathers had a lot of business entanglements that would lead one to seriously question whether they didn't have a conflict of interes

Certainly even the Founding Fathers had a lot of business entanglements that would lead one to seriously question whether they didn't have a conflict of interest (e.g., how much was Washington's decision to mount an army to secure the Ohio territory influenced by his own significant personal holdings there?). But it feels to me like at one point we had, to some extent, mastered this problem, and now we've moved away from even trying.