The big problem is people believing that there is any one such thing as inflation. There isn’t. The word inflation represents many, including wildly divergent, ideas. And many of the very different things represented by inflation serve very different purposes, and that’s why they’re changed, because different measures of inflation help measure different concepts. Core inflation is just one of many different measures…
If OPEC decided to stop producing oil altogether you bet there would be “inflation” caused by oil prices but that doesn’t mean the FED should be goaded into making changes to policy.