Of course I disagree and believe that Mohammed and Smith are a product of the Roman heresy that believes in continuing revelation instead of a closed canon.
Go ahead and show me from Scripture the notion of apostolic succession.
Mohammad married a Christian woman, whose Uncle was a monk and proponent of the Nestorian heresy, which denied among other things, Mary was the Theotokos, the God-Bearer or Mother of God. Thus, his heretical understanding of Christologly was a result of embracing Nestorianism, which was condenmed at the Council of Ephesus in 431 AD. For the record, many of your Protestants from various Protestant ecclesial communities embrace the same heresy as many Catholic and Orthodox posters can attest to on this site.
As for Joseph Smith, he was born in Vermont and like many there, were either congregationalist or did not belong to any organized religion. His uncle claimed one in the family would be a prophet and it seems that Joseph Smith, using his King James Bible [He was a King James Only type] got involved with a Methodist movement but rejected them believeing that he could take is King James Bible and studiy it for himself and determine the Truths of God and Salvation, etc.
Nope, Smith is Protestantisms baby and Mohammed and Islam can be rightly be seen as being a product of Nestorian heresy which rejects that Mary was the Mother of God in that she gave birth to a Divine Person [Christ] who had both a fully Divine and Human nature, without any confusion or negation of the other.