I am not really certain how to approach this kind of situation. If someone is convinced that their family's prior efforts to do genealogical research have been exhaustive and as in this case, they family has hired "professional" genealogists to assist in the research, it seems to me that any comments I might make about the sorry state of the documentation and lack of support for the conclusions would be instantly rejected. After all, who am I to question the conclusions of a professional genealogist, especially one who simply derived the entire line from an undocumented surname book written in the 1920s. In this case, I suspect that anything I say or do will only make my friend mad at me for questioning her family's integrity.
What saddens me about this situation is that it is so common and that the people who are accepting these unsupported conclusions about their family lines have not spent even a modicum of effort in examining the conclusions they inherited. Now, the main people included in this family line could very well be accurately recorded, but without documentation, there is no way to determine if the conclusions are correct or not. In this case, the line fades off into the past in Ireland in the 1600s. The Family Tree has an icon indicating that the immigrant ancestor's father was born "after the mother's death." In addition, the immigrant's mother was only 14 when he was born.
A superficial examination of the family of the immigrant as shown indicates that the father (the immigrant) was 45 years old when the first child was born and 67 years old when the last child listed died in the year that the immigrant father also died. This is entirely possible but certainly suggests that there may have been an earlier marriage.
The ancestral line back to the immigrant can be easily documented except for the children born after both the parents are recorded as dying.
The tragedy of this particular situation is that the descendancy view of the immigrant ancestor show dozens of immediately available Temple opportunities. The conclusion that "all the work has been done" has acted as a powerful disincentive to even look at the Family Tree and see all of the immediately available opportunities. In this particular case, the conclusion made by the family has also blinded them to the additional opportunities on the other family lines.
The real issue here is the common misimpression that genealogical research can ever be considered "completed." I have yet to see a pedigree that when closely examined did not have several obvious errors or unsupported conclusions.
In addition, the numbers always expressly contradict any claims to genealogical finality. It is true that some people cannot find their families. Orphans, foundlings and people who changed their names for a variety of reasons, will often effectively block any research. But discounting those rather rare problems, the vast majority of people have a discoverable ancestry for at least a few generations. Obviously, if you are an orphan, foundling or whatever, you will have to decide how much effort you want to put into overcoming the barrier to research. But if you find yourself in the situation where your family tradition and your own impression is that "all the work has been done," I suggest that you take a good, long, hard and critical look at your family's documentation and see if you can spot the incomplete lines and unsupported conclusions of the past.