A desktop publishing application from Microsoft that focuses on page layout and graphic design.
Microsoft decided to discontinue Publisher because of declining usage. The number of Publisher users had been steadily declining over the years. That's according to Microsoft - I don't have the numbers to prove it myself. Publisher had become a niche product.
Even without access to Microsoft's internal data, it isn't hard to see why the decline was inevitable:
1- Publisher makes paper-based projects, and the world is moving away from paper.
2- Many of Publisher's features were migrated to Word and PowerPoint. Not all features, and maybe not certain features that you rely on. But many features were migrated.
3- It costs Microsoft to maintain Publisher. Think of the costs to develop the software, to update it, to add new features and fix bugs. When faced with a declining user base, it becomes harder to justify the expense.
Publisher is hardly the only Microsoft product that faced declining use over the years. Among these are WordPad, Windows Media Player and Paint 3D. Left with an intensely loyal, but small user base and increasing costs, Microsoft chose, rightly or wrongly, to pull the plug.