The function names, arguments, and return values come from the biomaRt package, as this package is aiming to be a drop-in replacement for biomaRt.
Some arguments are no longer required, and are subsumed into the
ellipsis (...) argument. For example, the mart
argument is no longer required, as the connection to the database is
handled internally by the package.
Two main reasons:
There is thus value in keeping the biomaRt package alive to address more complex edge cases, and external Mart databases, while remart can provide a drop-in replacement for newer Ensembl releases.