This is especially important with really big applications like Microsoft Office 365 or Google's Business Suite: they are not just websites, but complex applications ... And in order to master that, you need the appropriate tools for it.
SEO - a possible disadvantage? On the contrary: Angular supports server-side rendering (SSR), which provides search engines with dynamic content efficiently and thus saves the crawl budget.
Angular also makes it possible to build Progressive Web Apps to provide offline functionality or access to sensors.
Angular is supported by some large companies such as Google. This results in better and better support for mobile platforms (NativeScript and Ionic).