Question

who called the real founder of the sultanate and why​

Answer 1

There is no doubt that Qutab-ud-din Aibak founded the Mameluk of Slave Dynasty

which had eleven rulers who ruled over Delhi from 1206 to 1290.

but aibak died beforen even consolidating his empire.

Iltutmish strengthened the Sultanate founded by his predecessor and was thus regarded as the real founder of the sultanate

hope it helps :)