The fact that projects choose to target a specific rendering engine as opposed to just writing web standards compliant code and having it work in any browser that follows those standards is precisely the reason why people (me, at least) are lamenting this decision.
With Edge, Blink, and Webkit competing for marketshare, app developers are forced to at least think about sticking to web standards or risk losing a chunk of potential users. In a world where only Blink exists and all developers care about is that things work in Blink, any new browser entering the market now not only has to worry about compliance with official web standards, they also need to worry about emulating the idiosyncratic behavior of Blink that developers have discovered and started abusing or taking advantage of. The actual standards essentially become moot and Blink becomes the real standard. And while, sure, Blink/Chromium is open source, with both Google and Microsoft heavily invested in its development and direction, who do you think is going to have all the power in making the important decisions?
With Edge, Blink, and Webkit competing for marketshare, app developers are forced to at least think about sticking to web standards or risk losing a chunk of potential users. In a world where only Blink exists and all developers care about is that things work in Blink, any new browser entering the market now not only has to worry about compliance with official web standards, they also need to worry about emulating the idiosyncratic behavior of Blink that developers have discovered and started abusing or taking advantage of. The actual standards essentially become moot and Blink becomes the real standard. And while, sure, Blink/Chromium is open source, with both Google and Microsoft heavily invested in its development and direction, who do you think is going to have all the power in making the important decisions?