5. why can't any attorney any client?

The main reason would be conflict of interest.

Conflicts of interest can be actual or perceived, but can have serious implications in either form. Attorneys can find themselves in hot water and even put their clients at risk if they aren’t thorough in their investigation of potential conflicts.

Mississippi’s ethics rules for attorneys say:

A lawyer shall not represent a client if the representation of that client will be directly adverse to another client, unless the lawyer reasonably believes:

(1) the representation will not adversely affect the relationship with the other client; and

(2) each client has given knowing and informed consent after consultation. The consultation shall include explanation of the implications of the adverse representation and the advantages and risks involved.

and

1.The attorney has consulted with and/or been retained by another person in the case or potential case.

2.The attorney has another client whose interests may overlap or conflict with yours.

3.The attorney has a previous client whose interests may be at odds with yours.

4.The attorney has “inside information” on the matter because of a former client.

5.Circumstances exist that may call into question the lawyer’s professional independence, loyalty, or confidentiality.