It is valid to point out that smallpox was only one disease that the Europeans brought to the New World.
But that is not the same as saying that the absence of smallpox would not effect history.
Here is just a little bit of smallpox's "contribution" to NW history:
1518: Half of Haiti wiped out
1519: Espanolla hit hard
1521: Aztecs suffer massively (helping Cortes)
1520's Yucatan hit.
Incas hit (the Incas seem to have been hit with smallpox and measles at the same time)
1560: Brazil's turn
1633: Indians around Plymouth hit
1640's-50's: The Jesuits spread smallpox to the Huron (the Indians form the belief that the disease was actually caused by baptism).
Also the Indians around Jamestown were hit by smallpox at this time.
1650: Jesuits again - this time in Ecuador. The Jesuits spread smallpox around a lot, and things were made worse by the Jesuits belief that converted Indians should gather in their own dense settlements - concentrating exposure.
1660's Indians in Massachusetts and New York areas devastated
1700: The Amazon hit
Early 1700's: Indians throughout New France and the Atlantic Coast devastated (again).
1801-2 & 1836-40: Massive pandemics devastates North American Indians.
If the Caribbean had a better survival rate (due to no smallpox) fewer African slaves would be imported.
If Aztecs were healthier, Cortes and his ilk might have failed.
Spanish would have a rougher time in a lot of places, really.
The Huron could resist the Mohawk but the Five Nations would still be more influential than IOTL.
If conversion to Christianity is less of a death sentence (due to no smallpox) then more indians convert. Indian "Praying Towns" would moderate European actions against Indians in general.
Europeans in NA would have a harder time getting established and a much harder time expanding toward the West.
The lack of smallpox does not create an NW Indian wank, but it would mean the Old Worlders would have to adopt different strategies than in OTL. Probably more trading and less outright conquest, for example. This would make things less one-sided toward the Spanish and the English.