I commented about this a few weeks ago here about this, but essentially: v2 allows you to block things you can't see, but you still probably don't want, like folks hiding cloud analytics behind CNAME cloaking to allow it to appear as a first-party site rather than Google Analytics, for example.

You won't "feel" this in your day-to-day browsing, but if you're concerned about your data being collected, v2 matters.