In general, scholarly monographs are valued as gatekeepers in some disciplines: literature, anthropology, sociology, political science, art history, ... But in most disciplines what counts are articles in the main peer-reviewed journals or contributions to selective conferences (e.g. computer science). Most high prestige departments where the monograph is traditional still demand one. But a rich vein of scholarly articles that are cumulative will often be more than enough. What matters is what the high-ranking scholars in your field think of your work.
There are not enough scholarly books published each year, or articles in the main peer-reviewed journals, to allow most scholars to have the requisite CV. Many universities have more relaxed requirements, with less concern about the prestige of the journal or the publisher. But the top-ranked departments are still quite conventional, as far as I can tell. They want faculty who publish in just those hard-to-publish venues.
But there is another crucial avenue--disseminating your work at meetings, conferences, and through drafts and preprints shared with the high ranking scholars in your field. If your work is strong, their judgments are likely to prevail.