When I introduced classes after variables, functions and scope... they struggled more.
Your experience is interesting.
I suspect that the problem with classes is that they look daunting and you have to know quite a lot before you can actually do anything. Most people just want to get on and do something, hence the "Hello World" and Blink programs. Then, of course, they continue along the same path adding complexity and by the time they ask for help they have invested time in their current flawed program and are often unwilling to throw it away and start again.
Perhaps part of the answer depends on the stage at which help is asked for. Someone asking for help on how to start a project may well be advised to use classes whereas somebody who has a working program with a problem might be helped further along their current path, albeit with advice to consider using classes.