Publishing companies have many benefits to songwriters. A publishing company/deal can be: (1) a bank to support a songwriter, and (2) a way to get the songwriters songs “covered” by recoding artists or placed in film/tv/commercials which generates income and credits for the songwriter. Publishing deals can also have drawbacks:
(1) the songwriter has to split the income and the copyrights with the publisher (usually forever), and (2) normally the deal is for several years so the writer can only write for the that one publishing company during the term and if the publisher is lazy or short staffed the songs might languish and the songwriter will starve.
Ben McLane Esq