Full Idea
Husserl substitutes his account of the process of concept-formation for a delineation of the concept. It is above all in making this substitution that psychologism is objectionable (and Frege opposed it so vehemently).
Gist of Idea
Psychologism blunders in focusing on concept-formation instead of delineating the concepts
Source
comment on Edmund Husserl (Philosophy of Arithmetic [1894]) by Michael Dummett - Frege philosophy of mathematics Ch.2
Book Reference
Dummett,Michael: 'Frege: philosophy of mathematics' [Duckworth 1991], p.20
A Reaction
While this is a powerful point which is a modern orthodoxy, it hardly excludes a study of concept-formation from being of great interest for other reasons. It may not appeal to logicians, but it is crucial part of the metaphysics of nature.