Why does the book claim that early socialism was “deeply infected by the Utopianism of past ages”?

Utopianism hints at the idea that everything will be perfect and that everyone will have everything they have ever wanted or ever needed. The roots of socialism lie in the idea of equality for all - no rich, no poor, no more gifted, no less gifted. Therefore, one could make the argument that socialists wanted to create the society that Utopians proposed earlier.