The founder may have had an "imperialist" mindset, where he dreamed to succeed to convert everybody to follow his rules, but in this respect there was no differ

The founder may have had an "imperialist" mindset, where he dreamed to succeed to convert everybody to follow his rules, but in this respect there was no difference between him and any European king or noble, or the Pope, or the Patriarch of Jerusalem, or any Chinese emperor or any successful ruler from any part of the world, at that time. So you cannot single out Islam as a special religion from this point of view. At most it can be said that all monotheistic religions are structured to support imperialism, because they replace the previous multitude of gods, all of which had their specific jobs, at which they could not be supplanted by others, by a single all-powerful God who knows everything and who can do anything, and this structure of the celestial realm is supposed to be mirrored on Earth, where there must also be a single all-powerful ruler, whom everybody must obey without questioning.