Absolute beginners may not able to write an actual proof that their answer is correct, but at least they can verify that it satisfies the problem (depending on the actual problem).

In any case, since the study of mathematics is cumulative. Even if the student can't prove or verify that their answer to a specific problem is correct they will eventually reach a point, often within the same problem-set, where inability to solve a problem will force them to encounter their gaps/misconceptions.

The most important thing in a mathematics text, as with any other text, is lucidity of writing and the preparation of the student.