Why does the Jamaat of the Promised Messiah still exist if it were false?

 Ahmadiyyah Counter Argument:

 "If the Promised Messiah was false his jamaat would not have existed till today."

For the sake of argument these are a few examples of the jamaats led by false prophets that still exist to this day. The deeper you dig, the more you find:

1)    Nation of Islam has existed since 1930 and perhaps still gains a few converts here and there.

2)  Mahmoud Muhammad Taha, who is known as a “Unorthodox Muslim Reformer” made changes to the shariah under the guise of being a Muslim Reformer. His spiritual movement still exists today, mostly in regions sought through asylums.

3)   Riyaz Ahmad Gohar Shahi claims that he is the Mahdi, Messiah and the Kalki avatar. His organization known as the “Messiah Foundation” exists till today. The death of Riyaz Shahi is however unknown.

These are only a couple of examples provided for the benefit of keeping the article short, the list of false claimants is endless.

So in a nutshell if the standard of "still existing" or "still growing" proves anything, it would prove all the other sects (greater in number) much more truthful than yours.