What does this mean? It means that there is value and meaning in the genealogies and significance in what appears to be the insignificant and mundane. Scripture is not the issue, rather the limited, fragile and biased vessels we are is the issue.
Nevertheless, there exists among some, a doctrine within Biblical hermeneutics which states that 'some scripture is written "for you" but not "to you."' This is best understood by considering an epistle of Paul: he clearly wrote the Epistle to the Philippians "to" the Body of Christ at Philipi, though he might have presumed it would have a wider audience than just the Church at Philipi. By this we understand that Paul wrote the letter "to" the Philippians and possibly "for" others who might read it.
But today this interpretive instruction is better described as method used to foist traditions of men onto unsuspecting minds and at worst, deliberately used for the corruption of the work of the Holy Spirit (1 John 2:27).
Consider then, this hypothetical scenario:
You write a personal and intimate letter to a third party, but include some things that are applicable to both your spouse and to the other person. You then deliver the letter to both people, with some additional instructions to your spouse that define which portions may be interpreted as "to your spouse." But all of the letter is to be considered "to" the third party, and is intended to be read and understood by the third party in that context.What have you done? From the perspective of your spouse, you have invalidated portions of the letter by making some sections and statements inapplicable to your spouse's intimate relationship with you. The other parts are just "for your spouse to read." She or He might gain some insight into your thinking or psyche, but any such information would be incidental and subject to his or her interpretation and application, since clearly your instructions were "that is not 'to you', it's just for you to read." In simpler terms, the 'for you text' is not reflective of your relationship with your spouse. But the entire letter is purely reflective of your intimate relationship with that third party.
The same is true with the doctrine of which I speak. The exception is that instead of getting a word from God Himself, we allow a third party (a Pastor or teacher) to define which portions of scripture are not valid for Jesus to use in our life and walk with Him. Thus we understand that the purpose of this doctrine is to define which things may be used to formulate or support various teachings and reproofs, and which ones are not suitable for such things.
In other words they're effectively teaching us that not all Scripture is inspired by God and profitable for teaching, for reproof, for correction, for training in righteousness. Thus, there are some parts of the Bible, according to them, that are not and never shall be considered as reflective of your relationship with God the Father, God the Son and God the Holy Spirit.
When you hear such a thing, you can be certain it is a tool being used to promote one's agenda. I vividly remember hearing the Pastor of a Good Bible Teaching Church (in the early 1980's) admonish his congregation that a particular book was helpful for understanding and comprehending what happened in the early Church, but that it was not ever to be used to formulate or support doctrine or teaching of any kind. In other words, it wasn't profitable for teaching, reproof, correction or training in righteousness. It made me wonder why he was teaching from it in the first place? But like the good little Baptist I was, I swallowed it hook, line and sinker.
What they're doing (whether they know it or not) is implementing a well known and often used debate tactic which states the following: "one may conduct a debate while attempting to exclude those things which damage one's position." Any good debater knows that when such a thing happens, the path to victory is found in the opponent's excluded material. This happens in court cases all of the time. It starts with the evidence and continues into the selection of the Jury.
The problem with it in Christianity is that most church members trust their Pastors implicitly - possibly through a form of worship I might add - and therefore blindly follow wherever they shall lead, never considering the validity of the precepts and statements leveled in their direction from the pulpit week after week, after week.
Nevertheless, to provide some practical examples, I have noticed that some Calvinists prefer to exclude the Old Testament when debating the merits of Calvinism, and Cessationists will undoubtedly exclude The Book of Acts (and sometimes portions of 1st Corinthians). In the least, they'll construct some other interpretive rule that appears to allow adherence to 2 Timothy 3:16, while shunning and excluding what they consider to be the less desirable parts.
So the next time some one admonishes you to not use this or that scripture as a source for doctrine, teaching, reproof and correction, do yourself a favor and ignore them - they're either just trying to win the debate, or they're just ignorantly repeating what they've heard from someone else.