Why weighted carries? WHY GOD WHYYYYY! 
To put it simply, Weighted carries are one of the few things in the strength world that give more than they take. A lot of Programs or movements with big return can sometimes also have a big Cost to benefit ratio 

When I transitioned to Strongman I immediately started doing weighted carries of every kind as a form of practice for the sport. But now, after 3 state titles, 4 International appearances and a slew of state level competitions, whether I’m in the off season or contest prep. Holds and carries are used not only as Event practice but to also help me get stronger, fitter, faster and keep me healthy 

On top of being able to recover from carries And holds easily compared to Deadlift, Squat or various other movements volume, the learning curve to perform these is quite low 

How long does it take some folks to TRULY learn how to Squat, Bench, Deadlift, Clean, snatch? Trick question its ongoing haha

Weighted carries i think are more discovered rather than learned. A person can learn how to pick and carry handles and a sandbag vastly quicker than a new Squat or Bench variation in most cases