Mid Train Locomotive

I am a railfan and have noticed that there has been an addition of a locomotive to the middle of the trains. I assume this is due to the newest software constructing the trains. I assume these locos are remote controlled or is there an engineer in the cab?

What is the benefits and the drawbacks of this? I assume the benefit is longer trains with the same amount of crew.

Distributed Power Unit, one or more locomotives remotedo to the lead unit(s). Generally, longer trains with better handling characteristics.