[SunkenCiv]

No, as in, cover bands never write anything.

[Dr. Sivana]

No, as in, cover bands never write anything.

There is no requirement to write if you can perform. Elvis Presley and Frank Sinatra wrote little, but made the songs their own. Artie Shaw did not write "Begin the Beguine", but he sure made it into something much better . (He improved on Cole Porter!)

Christopher Cross could write, but needed a LOT of studio processing for his singing to be minimally acceptable. (Carol King would be an example of someone who could do both. She is the exception.)

Most of the rockers who "write their own" cannot even consistent come up with true rhymes. (Elton John got around this by having a true lyricist, Bernie Taupin, among others to help most of the time).