I agree that the theory still stands but when put into practice then the results are mixed. Sometimes it works, sometimes it doesn't.
True, altho on the Federal level, it almost always works....because that’s the biggest tax load. I think it’s less predictive on the state and local level.
For example: I could have my state taxes cut by, say, a huge 25% - but it would still be just a rounding error compared to my Federal taxes.