Why is table-level locking better than row-level locking for large tables?

Question

According to the MySQL manual:

For large tables, table locking is often better than row locking,

Why is this? I would presume

Answer 1

from the (pre-edit) link

Slower than page-level or table-level locks when used on a large part of the table because you must acquire many more locks

use a row level lock if you are only hitting a row or two. If your code hits many or unknown rows, stick with table lock.