In this and the accompanying paper Jaworski and Przepiórkowski 2014 we suggest an answer in the negative and propose to approximate semantic roles on the basis of syntactic and morphosyntactic information.
in Zwierzę jest leczone z tych chorób 'An animal is treated for these diseases', in the VerbNet experiment the animal was marked as Beneficiary (by 3 annotators), as Patient (×3) and as Source (×1), and in the Sowa experiment -as Beneficiary (×2), as Patient (×2), as Recipient (×2) and as Result (×1).