But there are other problems. In Sahih Muslim we read about entire Surahs being forgotten. One of these Surahs was about as long as Surah 9, which contains more than a hundred verses. And yet Muslims remembered practically nothing from it.
Sahih Muslim 2286: Abu Harb b. Abu al-Aswad reported on the authority of his father that Abu Musa al-Ash'ari sent for the reciters of Basra. They came to him and they were three hundred in number. They recited the Qur'an and he said: You are the best among the inhabitants of Basra, for you are the reciters among them. So continue to recite it. (But bear in mind) that your reciting for a long time may not harden your hearts as were hardened the hearts of those before you. We used to recite a surah which resembled in length and severity to (Surah) Bara'at. I have, however, forgotten it with the exception of this which I remember out of it: "If there were two valleys full of riches, for the son of Adam, he would long for a third valley, and nothing would fill the stomach of the son of Adam but dust." And we used to recite a surah which resembled one of the surahs of Musabbihat, and I have forgotten it, but remember (this much) out of it: "O people who believe, why do you say that which you do not practise" (lxi. 2) and "that is recorded in your necks as a witness (against you) and you would be asked about it on the Day of Resurrection" (xvii. 13).
This Hadith raises some important questions. Why were entire chapters of a perfect book abrogated? Since Allah promises that he will only abrogate a verse if he gives something better in its place (2:106), what did he offer in place of these perfect Surahs? Further, Muslims typically claim that abrogation only refers to changes in practice, yet we can see that there were verses in these Surahs that had nothing to do with practice. Why were these passages abrogated?
The compilation of the Qur'an was clearly a very human process involving trial and error, educated guesses, faulty memories, fallible opinions, disagreements, mistakes, ignorance, and bad decisions. And we can't forget, of course, the pile of manuscripts reduced to ashes by Uthman in his desperate attempt to destroy all evidence that the Qur'an hadn't been perfectly preserved. The early Muslim community left modern Muslims with a huge mess to clean up if they want to cling to the false belief that the Qur'an was perfectly preserved. Perhaps dedicated Muslims should follow the example of Uthman and burn all of their ahadith, commentaries, and other writings which prove, conclusively, that Allah failed to protect his revelation (as he promised he would do in Surah 15:9).