Perhaps with Coinbase becoming and exchange, this will change anyway?
The so-called 'facts' in the article are incorrect. It appears they are mixing up "instant buy" (which appears to be done through a credit card and so is higher risk for them) and regular buys. Regular buys for level 2 look like they are $50,000/day. I logged into coinbase and the limits were $10,000/day since perhaps I haven't verified stuff.
Some references:
http://blog.coinbase.com/post/74631122841/a-change-in-limits-and-denominations
https://support.coinbase.com/customer/portal/articles/1412684-why-have-the-instant-buy-limits-changed-updated-1-27-2014