There is a defunct MMO I played for about 1 week and stopped called "Jade Dynasty".  It was just awful.  You could earn XP by meditation, sitting AFK in town meditating granted players experience.  Esper allowed you to bot the game.  After a week I decided "Jade Dynasty" was a game for little kids and not me.  There is such a thing as making the game too simple to progress.

I know we have AFK horse , fishing, skill, and combat training and that is more than enough for anyone.

НЕСТИНАР asking afk grind when you shut down black desert or your computer, so in НЕСТИНАР system you can fish, train horse, continue to trade when you shut down black desert or your computer

Hasn't been tested doens't mean it is a bad one.  More likely it was dropped for a lack of ideas to monetize it.  Though I could think of several. Limit to 3 alts, monetize more alt slots.   
A great way to balance it is by gear.  If the alt doesn't meet a zone GS threshold, it can't go there.  So it rewards gearing alts, thus people spending to gear them.

If it is only bringing back trash loot and limited amounts it isn't hard to balance. I think it would have to be, having a full loot option would be ridiculous.   Basically it would turn alts into workers in a way.  Balanced off that as a frame of reference would give a little value to alts than the daily passive which really nothing compared to the rest of the income you can make.  I'd say no to xp for this system.  We have an afk xp system, we don't need this gumming it up more. 

If the complaint is oh no more pay to win, common, the game is fully pay to win already. If you have a ton of money you can basically buy anything limited only by the market restriction of selling store items.  This doesn't change that. 

Any game that is giving you a resting bonus basically is givning you xp for being offline.  And there are a ton of mmos that do that. 

The bot industry suffers big loses when a game puts stuff like that in the game
Like it did with the autopath for example
And the kach up system that made whales mad cuz they dont want players to get free items so they can enjoy the content of the game FOR FREE and keep a big population so there are alot of charecters that make the game more alive when you chat or move around the world just enjoyng it
People say that its bad but i am 100% that they will use the auto stuff like they use the ones we have now :D

At this point, OP is just trolling fellas.

Stop falling for the bait and continue your day!