The problem with this method is that the person who is Proof texting usually gives their selected verses a meaning that may be entirely different from what the writer intended. The Bible is written in such a way that most verses cannot be correctly understood in a stand-alone fashion. The context of a particular verse, who wrote it, the time period in which it was written, where did they write it, etc. is needed to arrive at what God intended it to convey.
Proof texting can easily lead to wrong conclusions regarding what is the truth of God. An argument or doctrinal stand that relies heavily on proof passages is ultimately considered weak. In fact, those who preach and teach others based on such special passages in Scripture are generally viewed negatively by true Biblical scholars and those who seriously study the word of God.
A better way of understanding the scriptures than through proof texting is through what is called Hermeneutics. This technical term simply refers to the process or method of carefully analyzing what a particular passage might mean. Factors such as who wrote the passage, the period it was written, where and to whom the passage was written, etc. need to be considered in order to arrive at a correct understanding of what the Bible actually teaches. Additionally, any interpretation needs to consider what other related parts of the Bible have to say about what is studied.
10 For it is precept upon precept, precept upon precept, line upon line . . . (Isaiah 28:10)