Are they anywhere close to being as effective as minnows
My answer would be no. At times nothing is more effective than a minnow. They're made to tip a jig or other bait, not to be fished alone if I understand your question correctly though.
I don't think they hurt anything and I know quite a few guys that wont fish without them but I seldom use them myself and its mostly because I can't seem to keep em on my hook.