What's the point of smurfing with your bronze friends like this?

So basically in this smurfs case and the same as most other smurfs playing with their friend, the smurfer (obviously) has a main account that's around high plat/diamond and play normals and later throw ranked matches to end up in bronze so they can do. That's okay, but what I don't get is that they usually follow the formula of getting fed by beating down the noobs they're matched against (unless they manage to Vs the person with the higher normal mmr, then they insta lose), meanwhile the friends, who are noobs get beaten down most of the time, they get carried and not really get better at the game.

TL DR

I just don't get where the fun in watching your friends go 0/11 or feed every game and having them jerk you off as you carry by beating people who are a million division below you comes from.