There is quite a difference between conquering (and thereby assimilating) versus killing almost all natives and then populating the place with your own settlers..
The native population was not killed but rather decimated by disease. Pre-colonial population of North America was on the order of 60 million - there was zero chance European powers being able to hold that size of population over a period of time. Contrast that to Africa, which today has a minimal population of European descendants ... because that native population had immunity.
(Not saying this is the right perspective, but I understand why people would argue for it, especially when using ahistorical lens of today's diseases handling)
(#) Obviously the settlers would have preferred to keep the natives alive since then they would not have needed to ship vast quantities of Africans across the ocean to enslave, but could have just done that with the locals.
That's all I meant to clarify. You'd be surprised how many people today actually think that the native population was wiped out through deliberate and intentional action. Your wording made it seem you believed that as well, but that seemed to not be the case.
>Obviously the settlers would have preferred to keep the natives alive since then they would not have needed to ship vast quantities
That's a caricature.
Canada intentionally withheld food it owed to natives as part of treaty agreements, with the understanding that if a bunch of people starved to death, Canada wouldn't need to send as much food.
Similarly, disease was spread intentionally through small pox blankets, with the intention listed