This code doesn't work:

const files = [ 'file-id0', 'file-id1' ].map(DriveApp.getFileById)

with the exception Exception: The parameters (String,number,number[]) don't match the method signature for DriveApp.getFileById.

Although this works fine:

const files = [ 'file-id0', 'file-id1' ].map(id=>DriveApp.getFileById(id))

What's the difference of these codes? I cannot understand why the former doesn't work.

Note that DriveApp#getFileById takes only one argument as described in the document. I feel the exception being weird though.