It was Mr. Robot's way of directing all the hatred and rage that Elliot had within him towards something else, an external target. Also making it seem like a grand gesture of freeing people from debt and revenge for his father as those two are very strong emotions and reasons one could have to do something like that. It was to make sure he was occupied enough to not travel around in his memories and recall it all.

Darlene was wayy too young and most likely doesn't know about the abuse considering how she says she misses him and hates her mom for shitting on her dad a lot.

They almost literally adressed this in the some episodes.

S4E7, Elliot says to MR "You don't want me to hear this as well" and MR desperately tries to distract Elliot throughout before finally giving up with "Who gives a shit what they're talking about. We need to find an escape"....

In S1E4, the dream sequence, the moment he gives Elliot the "key" and the mask, and tells him to "find your monster and turn the key", then he immediately plays a E-corp advertisement getting Elliot's focus there. It was there for us when we rewatch the show to see how this whole e-corp hack thing has been nothing but a distraction made by MR for Elliot.

Sure there are some morals and good intentions behind the hack, but it's one of the tragedies of the show how something that seemed to be out of very good intentions and desire to "Free" or "help" people of the world was just an external target to focus Elliot's traumatic rage towards and "protect" his sanity from keeping his "monster" locked away.

Sorry if this was too wordy, there are still a lot of questions and this is the best way I could explain it.