Radical monopoly is a concept defined by philosopher and author Ivan Illich in his 1973 book, "Tools for Conviviality," and revisited in his later work, which describes how a technology or service becomes so exceptionally dominant that even with multiple providers, its users are excluded from society without access to the product. His initial example is the effect of cars on societies, where the car itself shaped cities by its needs, so much so that people without cars become excluded from participation in cities. A radical monopoly is when the dominance of one type of product supersedes dominance by any one brand.
Social media as a technology in the forms of Facebook/Instagram/Twitter could be seen as a radical monopoly for reputation, as is Linkedin for employment, colleges for education, etc.
I think Illich's criticisms of car culture pushed him outside the Overton window of policy making, but his radical monopoly concept is a useful critical tool for reasoning about tech and ethics. A counter argument could use the example that the discovery of fire created a radical monopoly on heat, and therefore it's so general as to be applied arbitrarily to anything you don't like. However, being able to think about the consequences of a new radical monopoly might have on some aspect of human experience is useful for anticipating policy options in response to dynamic technology development.