Even though the discussion this is branched of refers to standardisation of a specific rendering engine, to me the interesting part is on the original tweet.

I have never experienced the “This page best viewed in Chrome” message, but I have however seen “You need to use Chrome to view this page”, and actually think it is not that bad, because of where it is applied. I only saw this on “experimental” or “gimmick” pages, such as jamwithchrome.com.

This is a choice by this developers, regulated by either browser specific functions or cutting development time, when exploration of the medium is more relevant (to them) then wide availability.

Sure, it'd be prefarable (to the users) this would be done cross-browser, but it is a choice that does not necessarily undermine the open web. The problem before laid in holding back the web, but not on this specific cases. It's akin to a developer choosing a single platform to develop for (iOS, OSX, Windows, Android, Linux, and now in a way, Chrome, or even something like flash).

As long as we understand that this experiments are just that, experiments, and don't start actually developing for specific browsers where it matters, this is really not a concern.

Maybe there is something I'm missing, but right now I only see it as an issue that should not get out of hand, and not (at least yet) as a dangerous trend.

People say that having multiple browsers promotes innovation.

So if Chrome innovates with a new feature that is not supported by other browsers, what can you do?

Either A) use it, meaning your site will only work in Chrome and people will complain, or B) not use it, and all that innovation ends up being pointless.

So we have admit that with multiple browsers comes incompatibilities and things that only work in a specific app. That's the price of innovation.