Just because you say that doesn't make it true. That's a lie. They were not, and they launched with only bitcoin on their broker platform. Some of us that were around then know that, because we were there.
Stop spreading misinformation.
Feb 3, 2011 https://web.archive.org/web/20110203031942/https://www.mtgox.com/ First exchange Bitcoin
May 17, 2011 https://web.archive.org/web/20110517052225/http://coinbase.com/ No trade only Bitcoin name
Jul 20, 2011 https://web.archive.org/web/20110720154216/https://bitmarket.eu/
Jul 26, 2011 https://web.archive.org/web/20110726120745/http://btc-e.com/
Jan 14, 2012 https://web.archive.org/web/20120114174253/https://www.vircurex.com/ (lots of shitcoins from the get go)
Jan 20, 2012 https://web.archive.org/web/20120120102836/https://www.bitstamp.net/
Aug 5, 2013 https://web.archive.org/web/20130805091440/https://coinbase.com/ Seems first trades
Namecoin Launched: Apr 19, 2011
iXcoin Launched: May 7, 2011
Devcoin Launched: Jul 22, 2011
I0coin Launched: August 15, 2011