The concept of modern formal education is narrow and restricting. Projects and activities are usually picked by students with credit in mind, rather than actual learning. Not that learning never takes place in a formal setting, it does, by default, happen. However it is not the only way, and certainly not the best way for one to learn and gain true knowledge.
Knowledge comes from passionate seeking, and there is evidence that formal educational standards are low, and based on making enough credit to be able to pass a class via provided test reviews. This ensures that learning is limited to only those items that are to be anticipated on a graded test.
Most often than not, the knowledge ‘gained’ through a formal class for credit purposes is lost almost instantly or dries away from memory when not used. The point is that true learning comes from experience and the best lessons are self taught and may come from books and resources studied and committed to memory outside of a formal class setting, since it is self guided and fueled by a thirst for knowledge and not shoved in to a disinterested student’s unwilling memo.
Informal learning is that which sticks around for a lifetime, the truths thus learned are also more than likely to have been tested in the learner’s personal life.
To say that formal education is entirely useless and unnecessary would be a bold and untrue statement. It does depend a lot on the learner’s motivations. But the point that I aim to make is that I do believe that alternate means of education are not to be looked down upon. There are informal ways for one to learn art, philosophy, language, psychology and politics without having to enroll in formal courses.
Anatomy, physiology, mechanics, thermodynamics and specialized courses leading to complex problem solving related disciplines, and studies needing detailed knowledge starting from the cellular level to larger organs require much more study than one can do in a self guided, informal setting. Those would be best learned in a formal setting. Also, given the fact that such complex and time consuming courses require much passion and dedication in the first place, students who enroll usually want to learn everything there is to learn, to better themselves in the discipline and subsequent future pursuits that go along with the knowledge gained.
In conclusion, a formal education most likely ensures learning for students of highly diversified and specialized disciplines.