Why are papers accepted even if they don't release code or data to allow reproducibility?
There are multiple answers to your question.


Academic publishing assumes good faith. At least in the circles where the majority of people are genuinely interested in the advancement of science. This is the only viable mode of sharing scientific information between adults, although it sometimes fail as we all know it. Publishing should firstly serve the purpose of communicating results in a fast and convenient manner and second provide some sort of quality control. 
Sharing code and data is not a necessary condition for a study to be reproducible. It surely lowers the threshold of work that has to be done by other groups to reproduce the results, but clear and comprehensive descriptions of the methods and algorithm, as well as how the data was gathered, suffice. In fact, it's even better since starting from scratch will avoid the reproduction of results that are due to artifacts in the implementation or the original data.
Acceptance standards vary vastly between journals. Nowadays anything can be "accepted and publicized" providing you pay the "article processing charge". The question is where was it published and by whom. The most prestigious journals in my field have strict guidelines about the study design and sharing of materials and methods, the other ones don't.