quite the opposite. people wanting cameras without antiquated slapping mirrors inside were actively denied that choice for many years by the 2 inexpicably super-conservative companies that control 80% of the (stills) imaging market.
done rightt, cameras free of moving mechanical parts such as mirror/submirrorcassembly and mechanical shutters have clear and significant advantages. in all dimensions: IQ (eg no vibration-induced blur), operation and performance (fps, AF, silent, ...) and user interface (wysiwig EVF, less bulk).
mirrorfree cameras are the next evolutionary step for photographic equipment to overcome limitations imposed by its 18/19/20th century origins: digital imaging freed us of film/chemical complexities and the need to buy expensive materials from oligopolistic companies like Kodak. now - finally! - we are freed from limitations caused by moving mechanical parts. next stage will be computational imaging to free us from limitations of large, polished glass optics (lenses).
tiny solid state devices
are used to capture and create the vast majority of all images today. of course we can, should and will get such devices also with larger might- sensitive surface for higher technical image quality.
only Canon and Nikon have tried as best as they can to hinder, cripple and stifle that develoment by only offering marginally improved versions of their eversame mirrorslappers to be bought every other year by customers they considered locked into their "exo-system" with their proprietary lens mounts. they still try to repeat that business model today. but it does not work very well any longer. that's really why "the market is shrinking". lugging around big, expensive, conspicuous, clunky mirrorslappers has become "a nerdy aging male niche pastime".