Harms of reading one scholar

Usually, knowledge seeker is not satisfied with one scholar nor the people of one time, but some students limit themselves to one scholar after obtaining the principles of knowledge, so they barely could leave his writings and cannot take knowledge from someone else.

It is reasonable and expected that this matter occurs with grand scholars or scholars who have reached a high status in knowledge such as Al Baqillany, Ibn Hazm, Ibn Taymiyah, Ibn Al Qayyim, Ibn Hajar, and so on.
The problem may decrease and you find some of those students do not read but for contemporary scholars only, whereas others may only read the books of the Predecessors only or the latter, however the problem here is less that the first case.

This problem has many disadvantages on knowledge seekers, but it may be the worst of all to knowledge seekers.

Short-sightedness:

Of these harms is short-sightedness or narrow-minding as said by the language of contemporary people or lack of knowledge as ancient people call. We have to distinguish between the lack of knowledge which its owner knows about and the lack of knowledge which its owner believes that he does not have at all and that he is knowledgeable of everything; and that is the lack which we mean here.

The cause of the problem here is clear because a person does not know any other books but for this scholar only. So, if a knowledge seeker reads most of them, it is natural to feel that he encompasses most chapters of knowledge.

Boldness and haste:

This scourge is more damaging than its predecessor, which – however – a result of its findings because if narrow-mindedness is mixed with low knowledge, it suggests for a person that he is the wiser of all, the most knowledgeable of all, and the most understanding. Such people their opinions and views shall be based on this view. So, you find it full of boldness and haste, however the reasonable person who does not have a wide scope of knowledge. He should be moderate in his thinking even with people who preceded him hundreds of years. It is probably he understands their words limited as a result of the long distance. It is probably that they have explained their meanings which he did not understand it in another time or place.
Probably ha has understood the words as was but some distortions may hit it. Or the words have another meaning that the teacher or students or even Sheikhs knows.

Bad manners:

This problem also erupting from the previous because ignorance and narrow-mindedness suggest to him that bad-manners are the only defense of religion and that cursing and insults are only standing in the face of opponents! Moreover, he may think that obscene words and defaming are the two ways for Jihad in the cause of Allah with one’s tongue!

Imitation:

This problem is very funny because its owner claims to be a Mujtahid (one who exerts effort for legal opinion) in spite the fact that he imitates others because he does not leave the methodology of one scholar to whom he reads, but he rather cannot leave his opinions and views even if he sees him mistaken about one or two views.

Contempt of scholars and attributing lies against them:

This scourge is clear because he does not know that there are mates and peers to this scholar to whom he reads and believes that he is the most knowledgeable of all, so he despises the rest scholars.

Bad-estimation for his rank:

It is strange that those who read for one scholar believe that they reached the rank of that scholar just because they read his views or writings; which is a total ignorance and foolishness.
You see one from the followers of Ibn Hazm believes that he had reached the rank of Ibn Hazm in knowledge, and you see many knowledge seekers addict reading the words of Shaykh Al Islam, Ibn Taymiyah, and believe that they reached his rank in knowledge.