Because a) that sounds like you have a problem and b) that sounds like you blame your problems on other people, including people that the decisionmaker empathizes with more than he empathizes with you. That sets him to thinking whether you're going to blame him for hiring you in 6 months after you're fired from his company.
There's just no percentage here for you. (An American idiom: basically, no outcome of this line of thinking is going to help you.) Just handwave towards the economy and start talking about happy subjects.
Keep in mind that they're going to go back to the company, and if your characterization of your parting is different than that of the company, it will reflect negatively on you. If (and only if), during your parting, your boss says something along those lines, then you're probably safe in repeating it.
There's just no percentage here for you. (An American idiom: basically, no outcome of this line of thinking is going to help you.) Just handwave towards the economy and start talking about happy subjects.