To merely describe a practice is not to show its correctness. Not really - this would be to subsume foundationalism under some sort of coherence theory. The project is more like finding out what the correct way of weaving would be. A well justified belief may be false. I think that this statement misses the force of the whole problem of the criteria.
Every statement is supposed to require some justification.
That justification can either be another statement, a fact about the world, or itself. But if we are willing to doubt the original statement, we should also be willing to doubt its justificatory basis which leaves us with an infinite regress unless the foundationalist is right and there is some foundational belief which stops the regress. It's just that every belief must be justified by a belief which is justified by a belief which is foundational. Of course, this brings up for me a much more interesting question. It seems to me that to ask for the justification of a belief is to ask for an ethical act on the part of the speaker.