From the same link I provided earlier....

Ted Campbell, CEO of GrowPublic, Inc.,sums up the situation well:

It may take awhile for investors and issuers to come to the conclusion there is no real difference between an OTCBB® listed security and a Fully Reporting Issuer trading on the Pink Sheets now under the OTCQB designation. The recent move by many market makers to pull quotes on the OTCBB® platform causing a mass delisting to the Pink Sheets may be a precursor to the end of the importance of being listed on the OTCBB.