Does Lineage Matter?

There is much to do in martial arts about lineage and whether or not someone is 'legitimate' in the art, do they have the right lineage, are they authentic or whatever.  Does this matter?  Well, yes and no, it's according to what your goal is. It's the exact same as questioning someone's academic background and checking it out. If you want to know if someone actually learned what a specific school or teacher had to offer, then yes, it's important.  If I claimed to have studied astrophysics under Stephen Hawkings at Cambridge you would want to know if that is legitimate.  That doesn't mean that I can't know astrophysics or quantum mechanics if I didn't study under him it just means that I did not learn his direct take on the subject.  In the martial arts world, especially those originating in Asia, there is a lot of importance put on lineage.  This is because there have been a lot of fraudulent teachers over the years who claim to have studied with different masters but never did.  Also, many US teachers just made up their rank and affiliations to draw students.  They form their own committees to promote their rank but are not sanctioned by any established accredited organization.  They never really studied anywhere and were not sanctioned by anyone; but who could test that here?  There is also the issue of someone taking a weekend seminar and then claiming to know the art. Would you want to go to a doctor that only attended a weekend seminar on your condition or one that specializes in it?  I find this particularly prevalent among acupuncturists.  There's a slew of them who got accredited by weekend courses but few who actually spent years studying it.
 Along with this there are so many people that get a first degree black belt and then go open a school when in fact they have very little training experience.  So it is understandable why someone would want to know their lineage and how long they studied with that teacher.