A good explainer:
In 2017, the body responsible for standardizing web browser technologies, W3C, introduced Encrypted Media Extensions (EME)—thus bringing with it the end of competitive indie web browsers.
No longer is it possible to build your own web browser capable of consuming some of the most popular content on the web. Websites like Netflix, Hulu, HBO, and others require copyright content protection which is only accessible through browser vendors who have license agreements with large corporations.
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These roadblocks were primarily introduced to appease the media industry.
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Since the introduction of EME to web standards, the ability for new browsers to compete has become restricted by gatekeepers, which goes against the promises of the platform.