I've actually seen some fairly experienced paddlers doing that. Had to correct them.
Speaking of correction, but not talking about those I just mentioned.....some adults don't take it well. Worse than overconfidence is the guy who responds to correction with "I know how to paddle a canoe!"
You don't want that guy on any trip.
when I was teaching wilderness skills and paddling to youth, this was a far too common problem
with the parents! I've used a tried and true method for almost 50 years that was taught by my father, who also used it for decades- starting with a little info session with the group followed by a screening of Song of the Paddle, and a general rundown of their future "graduation" trip to whet their interests, next would be sessions learning about the safety, parts, and physics of the canoe and paddling with lots of dryland paddling time, a swim test, and a discussion at the end of each session, this would be followed by some actual on-water paddling and instruction (usually done over a weekend or two), and only after all that would discussions about an upcoming trip and the requisite planning begin, all this was done alongside of wilderness camping skills.
I've been accused of not knowing what I was doing (although I held over a half dozen certificates), my route, which I had done previously with kids as young as nine several times, that my boats (6 expedition kevlar Kippawas) were unsuitable for tripping, and that I was "reckless" with hundreds of trips and only ONE serious incident-a youth refused to follow saw safety rules, did not reach through the bow, and immediately filleted his thumb- that took 3 stitches
The most hilarious one though was the time we (my team) were told we had no experience- myself with literally decades of paddling experience and certifications in everything from a Scouts Canada water-charge and CRCA cert to DND medical first response, another trainer who was a semi-pro marathon canoe racer, an experienced wilderness paddler and white water instructor, and a provincially certified Conservation Officer, and others that came in as required...
Not one time did those same parents ever have any complaints AFTER the fact, but some did nothing BUT complain before the training...