FWIW I know for a FACT several of the top riders in flat water pro freestyle use trim for most every single flip.
I'm not saying it's right or wrong, but you can't put a blanket statement out there that they don't know what they're doing. I'm talking on the podium, this year, and in recent years.
Surf is another thing all together. I learned to flip without it in surf. It's not necessary. Do I still use it occasionally to ensure I don't tear the nose off a ski in 2' of water off a weak unpredictable gulf wave? Absolutely. You won't see me pulling it on chest high waves though. Is it a crutch? Of course, it makes it easier.. But so do aftermarket hulls. Where do we draw the line on what's ok to be one of the cool kids?
I just like riding, I don't care if you like my stunts, or how I come about doing them, all good times on my end