No - it favours voter equality and fairness, and removes a bias of the current system.
First Past the Post will always favour the largest two parties in a system, due to the 'strategic voting' effect.
Proportional systems remove that bias towards two parties, and treat all votes equally.
Yes - in MMP, small parties are more likely to be elected than under First Past the Post, but this is not a 'bias' of MMP. Rather, it removes a bias against small parties that is inherent in First Past the Post.