However the suggestion you make at the end, that we should only sanction Putin & co., is exactly the type of measure that would work in a democratic regime but not in an authoritarian one.
I can't think of a single case where a large authoritarian regime was handed off gently to a democratic one as a result of sanctions on the dictator.
I live in Serbia which was under heavy sanctions in early 90s: those in power have only gotten richer and more powerful during the time. Only after economy started recovering in late 90s, and people could afford to worry about "freedom" instead of basic survival did people get enough democratic momentum to vote incumbents out (sprinkled with a bit of West-supported protests to avoid a possibly rigged second round with 47% votes for opposition to 32% for incumbents in the first round iirc).
But sanctions did nothing to hurt those in power. They did plenty to hurt the rest of us.
In these situations, for republics like the United States, the best way to encourage the country to improve the standard of living for the citizens is via sanctions since it forces the country to sell these commodities at lower prices to a smaller group of potential buyers. If enough countries limit trade to where the country has to primarily rely on its own citizens for economic stability, they'd be further pressured into at least partially building schools and infrastructure and other things we/the United States believes should be a bare minimum for life.
National animosity will remain and it will be a political tool that can be easily put to use, but as long as there's money to be gained to improve life for your local population, trades will start happening.