Publishing is important for getting promotions or better jobs. For postgraduate students, both degrees and publications are important for getting jobs in academia. The degree to which publication is important varies in different countries, academic fields, institutions, etc. In general, publishing is more important in science than in the humanities, more important in more advanced countries than in developing countries, and more important in more prestigious institutions and the higher levels of education. Twenty years ago, it was possible to get a full time position teaching English in a Japanese university if you had an MA in English, linguistics, English education, or a related field.
Most institutions require publications.
C. Sharing Knowledge and Information Publication is not only for the purpose of getting jobs or promotions, of course. The main purpose of publishing is sharing knowledge. Researchers report what they have found, and other people can examine the results and the methods and even carry out similar studies to confirm the results, as mentioned above. If the new studies get different results, the results of both studies can be re-examined to find out the reason for the differences. Errors may be found, or the influence of other variables may be better understood.