The bibtex tag wiki entry reads: "This tag is for questions that concern Oren Patashnik's BibTeX program and its use." At the moment, there are 121 questions tagged with bibtex. In my opinion, they can be divided into three categories (nicely represented by the three questions with the highest vote number):
Questions about the BibTeX format -- its possibilities and pitfalls, and how to obtain/create/modify files in this format (Example question: What are good sites to find citations in BibTex format?);
Questions about the BibTeX program -- how to use it, and how to obtain/create/modify
.bst(BibTeX style) files (Example question: BibTeX style that groups by author);
Question that use bibtex as a complement/surrogate for the bibliographies resp. citing tags , although the problem is about formatting the
thebibliograpyhyenvironment resp. citation commands (Example question: Reduce bibliography to one line).
Being familiar with the BibTeX format does not equate to being versed in
.bsthackery. (Case in point: At the moment, I'm the top user of the bibtex tag, and I know next to nothing about the
.bstformat. I guess Herbert would be the top user of bibtex-program.)
The BibTeX format will be supported by
biblatexin the future, while usage of the BibTeX program as a backend for
biblatexwill be terminated (see PLK's comment to this answer).