The law does not permit a lawyer to avoid specialisation in certain fields. Theoretically a lawyer should be able to deal with any case based on existing law. In practice this is not really feasible.
The enormous effort required to make a lawyer not only totally familiar but an expert in any field cannot be undertaken by any responsible lawyer who wishes to best represent his client. Only a lawyer experienced in the respective field can know the right course to a solution at the first interview and can offer his client important guidance to reach the correct decision.
The saying holds true: Knowledge coupled with experience is skill.