[0] http://daringfireball.net/linked/2012/06/28/chrome-ios (linked by the article btw)
Android has no specific restrictions in place. Although it is the path of least resistance to use the built in WebView, since you now don't need to deploy your own.
[0] Including: Blink (Amazon Silk, Chrome, Opera), WebKit (BlackBerry, Dolphin, et al), Gecko (Firefox, Minimo), NetFront (Blazer). At the moment WebKit derivatives seem to be most popular, but several browsers re-build it from the source rather than just using Android's WebKit components.
That makes it possible to use extensions like ublock, for much better browsing experience than any browser without ad blocker can provide.
The word 'also' doesn't belong here. Browsers on iOS don't tend to use core iOS components (WebView) : they are forced to. Your statement really isn't a counter point.
[1]: https://en.wikipedia.org/wiki/United_States_v._Microsoft_Cor....