Intro
In 1907, MGA gives an exhaustive explanation as to why only he was given the title of prophet in the entire ummah of Islam.  This is a contradictory position, since we know that Ahmadis argue that prophethood is open and available for all.  Further, Ahmadis from the Qadiani sect believe that their Khilafat will last til the day of judgement.  Moreover, they secretly believe that only a Khalifa of Ahmadiyya will ever be able to claim prophethood.

Further, in 1916, Mahmud Ahmad vehemently wrote that even 1000 prophets can come and etc etc etc.  However, that is a cleverly crafted double-statement.  Since, in the depths of his heart, Mahmud Ahmad wanted to secure a Khilafat for him and his family.

The Quote
“”From one aspect I am an ‘ummatee’ [follower] and from another aspect, due to the beneficence of the prophethood of His Holiness [Muhammad], blessings of Allaah and peace be upon him, [I] am also a prophet. And the intent of [the term] prophet is only [to connote] that I receive abundant converse and address from God Almighty. The point is that, as Mujaddid Saahib Sarhindee [Sarhindee the Reviver] has written in his books, even though some individuals of this [Muslim] nation have [received or do receive] the special [treatment of] Godly converse and address and will remain special [receiving this treatment] till Resurrection but the person who is honored abundantly with this converse and address and who is abundantly made aware of matters of the unseen, that [person] is called a prophet. Now let it be clear that it
has been prophesied in the Prophet’s hadeeths that, from among the followers of His Holiness [Muhammad], blessings of Allaah and peace be upon him, a person will appear [or be born] who will be referred to as E’esaa [Jesus] and ibn-e-Maryam [son of Mary] and will be known by the name of [i.e., known as] a prophet. … And this thing is a proven matter that the extent to which God Almighty has made converse and address with me and the extent to which matters of the unseen have been made known to me, no person besides myself has been granted this favor in thirteen hundred Hijree [calendar] years. If some person denies this, the burden of proof is on his neck [i.e., on him]. The point is that in this abundant portion of Godly revelation and unseen matters, from this [Muslim] nation, I am the only special individual and all the ‘auliyaa’ [saints or friends of God] and ‘abdaal’ [saints who move from place to place to hide from public view] and ‘aqtaab’ [religious mendicants, holding a special title of rank] who have gone by before me in this [Muslim] nation – they were not given this abundant portion of this favor/blessing. Hence, for this reason, only I was specially selected for getting the name [i.e., title] of prophet and all the other people are not deserving of this name [i.e., title] because abundance of revelation and abundance of [perception of] unseen matters is a condition of this and that condition is not found in them. And it was necessary that it should have been so, so that the prophecy of His
Holiness [Muhammad], blessings of Allaah and peace be upon him, could have been fulfilled with clarity. Because, if other righteous ones who have preceded me, [if] they too, to the same extent, had received a portion of Godly converse and address and unseen matters, they would have become deserving of being known as prophets [and] then in that case a crack [or fault] would have occurred in the prophecy of His Holiness [Muhammad], blessings of Allaah and peace be upon him. That is why the wisdom of God Almighty prevented those respected people from obtaining this favor in a complete manner, just as it appears in authentic hadeeths that such a person will be one only [so that] that prophecy be fulfilled. [RK, v. 22, pp. 406-407; starts at 4th line from top of p. 406, skips some lines below middle of p. 406, then goes on
till about middle of p. 407; Haqeeqat-ul-Wahee; published May 1907]”””

1908 Quote
“””This word ‘nabuwwat’ [prophethood] that has been adopted [i.e., adopted by Mirza Ghulam Ahmad] is entirely from God Almighty. A person to whom some thing [some item of information] is abundantly conveyed by God Almighty, by way of prophecy, [such a person] is referred to as a ‘nabee’ [prophet]. … Remember that the chain [or system] of prophethood will remain established till Resurrection [‘silsilah-enabuwwat qayaamat tak qaa-im rahay gaa’]. [MALFOOZAAT, v. 10, p. 451; recorded under the date May 25, 1908]””””

Some conclusions
It seems that MGA was looking to deter Ahmadis from claiming prophethood.  This is the argument that him and his team came up with.  MGA claimed prophethood in 1901, and claimed that anyone could become a prophet, however, just a few years later, he changed him mind.

MGA and his team also forget that in the 1898 era, MGA wrote that:

“”””It is written in Prophetic Ahadith that at the time of the advent of the Promised Messiah, this dispersal of spirituality will be such that women will begin to receive revelation, juveniles will prophecy and common people will speak with the Holy Spirit.”””  See here.