Essentially a qualification is a constructed course validated through an examining board or (in more obscure areas of study) a more experienced and qualified practitioner in your field. I know we are all aware, qualifications are not divine secrets passed on to a chosen few only become decipherable to mortals via a financial transaction.
Learning your times table without an accreditation is still your times table (showing my age there).
In terms of insurance - you may need a recognised exam body to prove your skills are to the standard claimed or insurance could be void, but not necessarily - that I would look into in more depth before making plans...
I'm new to this and it is just one opinion, but - personally - I think that you don't automatically need a course for every new technique and medium used in order to be able to deliver a professional and safe service - with the proviso that you are a competent, dilligent student and academically minded enough to know whether you are meeting professional standards or not. The main thing is that we never do anything unsafe, never lie to clients and never over promise on what we can capably deliver within our skillset. Certification is an objective and measurable proof that as a students we've reached a predetermined standard of learning on the subject studied and understand our subject well enough to qualify - or just have a good memory 
I should add - I'm not in any way anti courses in order to improve skillsets - sometimes it's the only safe option especially for the self employed (E files being a prime example).... I just think that done properly, self education is where all industries began in a way.... 
No shade to anyone - just giving my 2cents - pax 
