Why rival browsers want EU to take action against Microsoft Edge

Several web browser developers have urged the regulators in the European Union (EU) to take action against Microsoft, alleging that the company is unfairly promoting its Edge browser on Windows at the expense of competitors.
In a letter to the European Commission, Vivaldi, Waterfox, Wavebox and the Open Web Advocacy group argue that Microsoft is exploiting its dominance in the PC market to give Edge an unfair advantage, as per news agency Reuters.