As by way of example, it's obvious to everyone who isn't a Patterson or Patterson-like life form that for all intents and purposes, April was a neglected orphan being raised by her grandfather. For very self-serving and ridiculous reasons, her parents seemed to do very little in the way of actually bringing her up or imparting values or anything like that. Someone cruel and heartless who didn't understand how horribly Elly and John had to struggle because they had to wait more than five seconds for a goal to be accomplished and also had to do that themselves might confuse them with dimwitted, negligent and short-tempered baby-sitters with an attitude problem whose baleful and useless interference only served to make the work of her primary caregiver harder.
This, I should think, is why they're at pains to sell April on the idea that Becky is bad news while Eva is great. You see, not only is Becky from a broken home and thus to be avoided because of some dread that marital disharmony might be contagious, she has terrible information to impart. Just as Gordon used to be bad for Mike because he used to regard Elly as being a short-tempered idiot who overreacted witlessly to harmless phenomena such as dressing up like Bowie for Halloween, Becky tells April that parents are capable of using their children as weapons in some sort of emotional war. Worse still, she says something VERY dangerous about how physical and emotional distance have very little to do with one another. If April were to be exposed to that sort of darkness, she might start to thinking that it doesn't just look as if her parents don't actually care for her much and are mostly out for themselves.
How much better for April to have Eva slam her down when she questions if her parents actually like her. Most of us can see that she's making the same stupid mistake Weed does when he assumes that since his super-busy but loving parents do not teleport to his side when he feels low, they do not care for him. Since she's the "Where is X when you need him/her" kind, she's there to sell the Martian on the idea that since her emotionally absent and distant parents are hovering over her congratulating themselves that they're finished being her mom and dad, they do care for someone they don't know that they regard as an inconvenient poor relation.