As Plotinus said, it's usually because you try to use unsuitable tools. Suitable, but low quality tools typically results in poor results (i.e. low quality items), but the tasks can be performed, normally.
In addition to tools, injuries can cause issues, such as e.g. only have one usable arm for tasks that require two, and I believe starvation can weaken the character to the point of being unable to perform some tasks within a reasonable time.
It was news to me that fine stone axes actually can be used to make boards, but, on the other hand, it seems like an enormous effort is required before you'll get that axe...