Well, considering a lot of the best riders in the business ride with fins, I would disagree that fins are a crutch in general. For some people maybe. For me it's all about tuning the board I am riding for my style. I've ridden most of my boards over the years with no fins, but my current board has a set bolted on.
I think fins slow the board way down. I know they will expose flaws sometimes...like trying to spin off the wake, or in your case, maybe trying to spin your olie 180 a little too early, maybe? In this case they may help you fix a bad habit.