Their own Google Play would be impacted otherwise. Good to hear, since the only thing I use Chrome for is Google Play (and any other, one-off, old-fashioned sites which require Flash). Why in the world does Google still require Flash for... anything?
Great, so we can now expect more and more sites to start playing "null" audio as a "workaround".
...that would explain why flash files with no sound seem to 'pause' (or at least, run very, very slowly) when in a different tab.