I have met some proper idiots on the Llangollen. The majority of them were on hireboats. Therefore most hireboaters are idiots.
Except of course they aren't. The majority of boats moving on the Llangollen in Summer are hire boats, therefore the boats you are going to meet are hirers. A proportion of these are first timers and most of them meet their first lock at New Marton. So at New Marton you have a stressful busy section of canal, with a number of inexperienced boaters. The idiot count therefore seems quite high, but in reality it's just busy and sometimes a bit slower than it might be.
The real idiots are a very small proportion - all the cliches - the drunks, the speeders, the arrogant tosspots, and because of the sample at New Marton being mostly hirers, it would appear that the population of hireboaters has a high proportion of buffoons.
So lets look at a different set of locks - Hurleston has a number of hire boats, but because of the big marina at the top, and the logistics of a weeks holiday, the sample of boats here is usually much more diverse. The proportion of idiots is probably the same, but the number of hiring idiots is smaller.
tl;dr There are idiots on boats. How many of them are hirers is a matter of perception, based on location, time of the year, day of the week, time of day even. Oh, and personal prejudice.