Shakespeare vs. Chaucer

During the Taboan conference, most multilingual writers said that the reason they write in more than one language is that they find any language limited and not able to express what they really want to say. Does this mean that, in theory, everything else being equal, someone writing only in one language cannot express as much as someone writing in two or more languages? I mean by "everything else being equal" the real possibility that one writer has more to say than another and, therefore, is more in need of another language than the other. Speculatively, is Shakespeare as a poet worse than Chaucer whose Canterbury Tales was a combination of (Old) English and French? Btw, it is legitimate to say that one poet or one work is worse than another, because we say that all the time when we judge literary contests, whether small ones or the Nobel.