Because America, the country with mostly native English speakers, is 4x more populous than Germany.
Because the British Empire (and the Spanish and French empires) killed a great many of them, and forcibly imported their own cultures, people, and languages.
Which is unquestionably imperialism, and undoubtedly cultural. Hence: cultural imperialism.
If it weren't for cultural imperalism, the only native English speakers would be the population of the UK, which is about on par with Germany.
;-)
Making up artificial delineations on arbitrary segmentation of time gets a bit wearying.
Various cultures have their time in the sun and then retreat- it’s as old as humanity itself.