A wealth of information in their barest form. Intimate knowledge of personal information that might not otherwise be presented, a way in, an advantage.
Maria can’t help but acknowledge the advantages of certain relationships, and this sometimes gets in the way of her actually nurturing a connection with another person. There’s a slight fear there- of getting too close, of otherwise being accused of capitalizing on the gain for her position. Nick Fury had always lectured her on the difference between trusting someone and calling someone your friend.
( There are certain responsibilities associated with the latter, responsibilities that could cement your loyalty in a world that depended, mostly, on S.H.I.E.L.D.’s neutrality. )
More recently, though, she’s found herself reaching out for those connections. Sue and Sharon, occasionally Natasha. Harry, Bruce. There’s something good to be said about knowing you have people on your side- not because they’re paid to be, and she’s intent on working to keep them that way.