What is learnable by web-based instruction depends on learner's readiness.
For example, in most cases, it is difficult for inexperienced person to master physical skill (such as swimming) web-basedly.
But, for experienced one, there is definitely a place where web-based instruction becomes effective.
Generally speaking, self-teaching by web instruction material works well for those who know the issue and want it to be developed thoroughly, minutely, or in an easy style.
Remark:
Whether a web-based self-teaching works for initiating a learner into an inexperienced subject depends on the subject.
