No, but there's a budgetary reason why cheap mixers might not be as good as an interface.
Checking prices at Sweetwater (just as an example) a Focusrite 2i2 interface is $150. A Behringer 802 is $65. Despite the price, the Behringer includes a whole lot of extra knobs and connectors, including the toy EQ on the channels, an FX send, etc. etc. There's no such thing as a free lunch so, in order to pack all that in for less than half the price, corners are being cut somewhere.
Even so, I'm not saying that the 802 is necessarily bad for the money--just that you're paying for extra bells and whistles you don't need, almost certainly at the expense of audio and build quality.
The best advice in this thread was earlier on when several said don't use a mixer unless you have a specific need (monitor mixes being an example given) for one. If you have such a need, then check features and make sure the mixer you buy has the ability to do what you need...for example sufficient pre fade auxes and flexible monitor routing. Far too many people buy a mixer because they just assume they have to work like Abbey Road--and end up buying units that add nothing and may take away something.
As mentioned, I use a biggish mixer when I need one...but resort to a small, cheap two channel interface for the simple stuff.