As a songwriter IMO would only needs a piano or guitar that would be sufficient to write songs on a basic level scratchpad,....and let all the rest of the magic happen in the studio with singers and some good musicians.
And where does one get the $'s to pay for such talent and studio time
Most stuff "recorded at home" wont be commercially ready, if and when someone signs you to a deal for that song money will be no object if it's worthy to make them and yourself a nice profit. Many hit Songs have been written on toilet paper

FIRST before they make their possible journey to Hits-ville afterwards in a studio before a Master cut..