But there was an official preaching.
In 571 A.D the Holy Prophet (pbuh) was born and this marked the starting of the Era of Islam.
He preached. Battles and Wars took place. Blood was shed. People converted. Even people like Abu Sufyan who were sworn enemies of Islam converted to Islam.
Had such a preaching took place in other areas of world, won't Islam have been established as a majority religion there today?
Since it didn't take place, that means it is part of Allah's plan.
That was because, people didn't know about Islam in those days. Prophet(phuh) have completed his work and completed Islam.
Nowadays, most people will know about Islam. And if they didn't know anything about Islam, they might go to heaven.
By (the Token of) time (through the Ages), (1) Verily Man is in loss, (2) Except such as have Faith, and do righteous deeds, and (join together) in the mutual teaching of Truth, and of Patience and Constancy. (3) Al Quran [103, 1-4]
Surah Asr: the above 4 conditions HAVE TO BE FULFILLED IN ORDER TO ATTAIN JANNAH. So DAWAH is an integral part of the condition and so is compulsory on us Muslims to do so: The prophet said- Convey from me even if you know 1 verse........ So there would be muslims who pray 5 times a day,etc but do not fulfill the 4 criteria, they wouldn't enter Jannah SO your previous point about OSAMA bin laden, he surely didnot spread Islam.... he degraded us muslims