Article is in error to say you can lower costs by working aboard.

Generally, the per-day cost of travelling this way is the same or higher than a cruise ship, at list prices.

However, cargo ships tend to cross oceans and take routes that cruise ships don't. That's their advantage

The disadvantage is that the per-day cost is double the discount price you can get on a cruise ship.

With a bit of planning, cruise ships cost about half as much per day.