yes, I agree British colonialism is not a sufficient condition for making English the dominant language. that does not invalidate my original statement.
I can’t imagine imperialism was a significant factor. Relatively few people need to interface with the imperialist power; but the new wealthy market imperialism makes available to you incentivizes you to learn the language of that market.
Imperialism was most definitely a huge factor - that's the sole reason so many countries have English as an official language.