With most trades it is a simple matter to see their work and get a peer review as well as obtaining references; so everything is transparent
In the case of the accountants everyone is going to proclaim that they are the best and no one in their right mind is going to admit to anything else - but how is the public to know whether one person is better than another. Furthermore, even if their knowledge is inadequate for the job in hand will it be declared or is the client taken on in the hope that one can get up to speed at a later date?
The number of basic level questions being posed on Aweb is interesting because they address issues that most have long forgotten or take for granted - it is not really about lack of knowledge because everyone goes through a learning curve, but to what extent should it be at the expense of the client (you don't have brickie producing a crooked wall because he is learning on the job).
However, bearing in mind the Aweb user profiles, a great many of these questions come from sole traders/small practices who deal directly with clients. Therefore the inevitable conclusion is that in some instances clients are being taken on by those with insufficient knowledge to do the job - although, whether this is/should be declared is an entirely different matter
So the question is – when building a house would you take on a plumber who could replace the washer in a tap but not install a central heating system? – and how can a member of the public ensure that they take on an accountant who has sufficient knowledge/experience to provide a service