When Google Plus was pushing real name rules, a lot of people said "where's the evidence? where's the data driving this decision?" They didn't have any. Google claimed that real names encouraged better social behaviour. This is something people commonly assume about real-name policies — but no-one, including Google, has ever supplied actual evidence of this, rather than personal feeling and assertion.
In fact, what evidence there is points the opposite way: South Korea required commenters on sites with over 100,000 users to supply their Resident Registration Number (national identity number), and this reduced malicious comments by ... 0.9%. http://english.chosun.com/site/data/html_dir/2011/12/30/2011...
So the evidence is against the claim. If you have good evidence for the claim, you'll be the first.