The pagan Arabs were mostly illiterate and very rarely had the facilities or the wherewithal to put down in writing the verses of the Quran. Most of the Quran had to be memorised by those who were attending Muhammad at any one time.
Since Muhammad had to inform some of his immediate followers of his alleged ‘revelations’ at different times, in different places to different companions – over the incredibly long period of twenty three years – it was i…mpossible for him to keep track of the verses, their contents and to which Sura they belonged.
He was after all, giving different versions of a verse to different companions at different times and different localities. This caused of course, dissent, consternation and bewilderment among his followers.
When confronted by the numerous and very embarrassing discrepancies, Muhammad escaped this dilemma by informing his gullible and ignorant followers that the Quran was ‘revealed’ in SEVEN different ways, modes, versions or dialects.
Allah, who gave the Torah to Moses in only one form and in a singular language, had to give the ‘glorious and inimmitable’ Quran in SEVEN different ways.
The reader should be reminded that many of the MEMORIZERS of the Quran perished in the earliest battles of ‘Islam’, BEFORE the Quran was finally collated and collected.
Hence, even according to the Hadiths, innumerable verses were lost in that way as well as in other ways as detailed in ‘The Collection of the Quran’ section.