Interesting quote from the same Cambridge link: in a newspaper article about language in Singapore in 1937, a British writer wrote “ There is, we believe, no record of the number of tongues spoken at the original Babel but we have an idea that if the truth were shown Singapore would be found to have put its ancient prototype into the shade’.” (He believed the challenge in reaching English proficiency was because we spoke way too many other languages.) I quite like that quite out of context, though I see the multilingualism as a strength, and our variety of English types as an interesting quirk as well.
I do worry that decades of language repression in favor of prestige languages (Mandarin over dialects, the ‘right’ English accent versus our natural ones), have killed a lot of language variety. And proficiency.