The 1980s saw the major record companies of CBS, EMI, Festival, and to a lesser extent Polygram, RCA, and Warner, banding together to release compilations. I’m not sure what the authoriries had to say about this, but they got away with joint production of CDs and warehousing/distribution.
This all meant that K-tel, JB and Concept, as well as the other smaller independents were being locked out to the market. Maybe it was the head office accountants of the majors that saw the value in reissueing the singles in a half yearly package, but there was increasing pressure from overseas. As licence fees increased and there was more pressure on artists to make money, this was the begining of the end for K-tel, Concept and J&B.