We have a Help Center posting that outlines this. For your convenience, here is the text from that page:
How come I can't comment as often per day as I used to?
In January 2013, we surveyed thousands of Ask.com Q&A Community members to find out what people love about the place, and where we can improve things. One of the ways in which survey respondents were almost in total agreement? The need to focus more on questions and answers.
We agree! We love the ability to get to know people in comments, but our purpose has always been - first and foremost - to help people connect with answers to their questions. For that reason, we've changed the number of comments that can be made within a 24-hour period, but question and answer limits remain plentiful!
We appreciate everyone who took the time to respond to our survey, and we're glad to continue helping the Ask.com Q&A Community be the place that everyone wants it to be.
Please note: creating extra accounts to bypass this guideline is against our Community Guidelines.