We will see after reading what King Sejong had to say in 1429.
The Veritable Records of King Sejong, Volume 44, Year 11 (1429), Month 5, Day 28, Entry 4
○上謂代言等曰: “儒生能治四書五經及《三場文選》、《源流至論》之類, 亦可能製述, 而應擧矣。
The King said to the royal secretaries, “Confucian scholars can master writing by first studying the Four Books and the Five Classics 四書五經 along with such books as the Collection of Selected Writings for Examinations [of the Yuan Dynasty] (C. Yuanchao sanchang wenxuan [元朝]三場文選) and the Foremost Discourses on Origins (C. Yuanliu zhilun 源流至論). [That would be sufficient] to prepare them for the state examinations.
不此之急, 專聚儕輩所述, 以爲抄集, 或遇疑似之題, 剽竊書之, 靡然成風, 近日視學, 令製箋文, 皆竊用權孟孫都試居魁進《豳風圖》箋, 故予不取之。
“Instead of making this their priority, [today’s young scholars] are intent on collecting what their contemporaries wrote and compiling them into booklets. When they encounter a topic that appears similar to one found in such compilations, they plagiarize the latter. Following bad examples, they have turned this into a common practice. Recently, when I inspected the Royal Confucian Academy, I had its students compose a memorial. All of them plagiarized “The Illustration of the ‘Airs of Bin’” 豳風圖 that Kwon Maengson 權孟孫 presented and for which he won the first place in the special royal examination for ranked officials. Thus, I selected none of them [as a winner].
雖平時製述, 竊用抄集, 固非識理儒生所爲也。 況予親臨試士之時乎? 予欲痛禁, 然非所以令臺諫, 禁止之事也。 爲之乃何? 其議于卞判府事。
“Even when writing in normal times, conscientious Confucian scholars should never plagiarize from compilations. How much more so when I personally test them? I wish to prohibit this practice thoroughly. However, it is not a proper course of action to employ the service of inspectors and censors to do so. Discuss this matter with Superintendent Byeon [Gyeryang] 卞[季良] 判府事 regarding which measure to take to prevent this.
予心以爲四書五經之外, 抄錄中朝有名抄集及東國名儒所製若表箋策問之類, 印出頒行, 悉禁鄙拙之文, 以杜詭遇之門。 若其譎詐之徒, 不悛前行, 則置之度外, 亦可也, 幷此議之。”
“In my view, it would be best to print and distribute compilations of famous writings of China and selections of memorials and essays on policy authored by the Confucian luminaries of our country and then to completely ban the use of coarse writing examples, thereby closing down the door of craftiness. If, however, it is expected that cunning men would never repent of their previous behavior regardless, then it might be advisable to give no thought to this matter. Deliberate on this possibility as well.”
Now one can realize that plagiarism was severely criticized by King Sejong, who not only expressed his concern about plagiarism among young scholars but also revealed his idea for stemming it.