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

A row Table level lock is better for a large table where major data modifications are taking place. This lets the system contend with a single lock on the table rather than having to deal with a gazillion locks (one for each row).

The RDBMS automatically escalates locking levels internally.