Sure it would, but isn't diversity a good thing too? Specially if you consider long term scenarios.
There is quite some diversity, since unlike basically any other technology of comparable complexity there are already three fully independent browser implementations, with a fourth one (servo) coming. But they are not fully compatible and will never be, which is why every website has to be tested and adapted slightly for each engine.
Even more diversity will actually weaken the web as a platform, not strengthen it. So, no, it is probably not a good thing if taken too far.
And, besides, how likely is it that this particular implementation will ever come close to the existing ones in terms of compatibility? Highly unlikely.
In the case of gngr, it can't even render Reddit or Google.com correctly. Can you imagine how badly it breaks on more complex sites? Can you imagine how broken its core is?
Diversity is good, but it requires resources, lots of them.
Compatibility is a slog, but it's a doable one. Remember, to be usable on a lot of real-world sites you don't need to catch up with Firefox Nightly or Chrome Canary - you only need to catch up with IE6, or maybe IE8.
Of course, I'm also disappointed that they didn't choose to build their browser on Servo instead. ;)