Because ABDC has one drawback that for evaluation, the publishers outside Australia cannot submit their journals. They really need to find a trustworthy academician from Australia to submit a journal to ABDC
It is complicated to say which one is better because the objectives, scope, coverage, and contents of ABDC and Scopus are different. Scopus is considered to be one of the largest databases of peer-reviewed literature in the world. Global university ranking bodies like THE, QS consider Scopus database in world university ranking. Scopus may be compared with Clarivate /Web of Science (SCI, SSCI, ESCI). On the other hand, ABDC ranking focuses on the ranking of basically business/management journals by an Australian body (ABDC). ABDC may be compared with ABS/AJG raking of CABS, UK. Many business schools around the globe follow the ABDC/ABS ranking of journals.