Obviously it's not worth the investment in terms of money, time, expertise , or people would do it.
To have you shyt on radios all over the world, released in stores at the same damn time, TV interviews, marketing all over the world, internet, in movie; commercials, awards and all that shyt at the same damn time is too much for these dudes. Jay and Puff would probably have to invest all their money (ie risk all their money) and years of building a label to have the same services to themselves as a major label offers and for what? Have a few Jews of their payrolls? Let's not forget that these people are artists, entertainers.
There is a reason to why the major labels are major companies.
UMG > Vivendi: multi billion dollar corporation since 1843
Sony Entertainment > Sony: Billions since 1946
EMI > owned by Citigroup 3 trillion in assets
WMG > Used to be Time Warner billions since 1918