The advantage is that the understanding of a concept framed in one of these regions, can spread more easily across all English language regions.
Which is probably a major reason English is one of the richest languages we have.
I know this is how you think, this is the rigid terms in which computer programmers, engineers and people bound up in totalitarian thinking in some form or another ALWAYS frame things and honestly I understand, it is very similar to how to very effectively tackle a technical problem.... but this is not a technical problem this is a question of life.
You will never come up with the concept or learn how to explain it to people without the diversity, intelligence, creativity and new ideas that a diversity of languages and really everything brings to the table in the first place and the person you are speaking to won't be intelligent enough to understand in a meaningful way either. You are looking at the inefficiencies of diversity and dismissing the stability, growth and innovation it brings in a way that worries me because I see the ideology everywhere.
How is you argument fundamentally different than just rephrasing a totalitarian argument in terms of language, "It would be better and more efficient if we only had ONE LANGUAGE, ONE GOVERNMENT, ONE WAY". No it wouldn't, it would be efficient at conveying simplistic, empty instructions across an utterly broken populace unable to think for themselves in any meaningful way which is in my opinion quite a distasteful form of efficiency.
You have just reframed the concept, role and artistry of language in a way where you have disguised how threatening a loss of diversity in it will be towards pushing things into collapse, degradation and violence of some kind.




I don't need to, try actually talking to an indigenous person, evolutionary biologist or an environmental scientist and if they can stand talking to you for more than 5 minutes they may explain it to you.
I don't need to, that isn't my point, my point is you are trying to take a shortcut to intelligence and communication that involves hurling empty symbols back and forth at strangers, that will never lead anywhere unless you and that stranger start to develop a unique language specific to that context that honors and remembers that context... and yes we can do that right now but guess what makes human language such a gift to us that it was passed down to us and entrusted in our stewardship? Do you not see how you are spitting on that gift with your words?
Yes, you can always plant a new 200 year old tree if you cut the 200 year old tree down... but you will have to wait 200 years to experience the true complexity and power that is latent in the seed again.
If you think I am arguing for NOT understanding each other you aren't actually listening to what I am saying, what I am saying is you are lying to yourself about being able to convey anything once you reach the point you desire and admire and seem to think would be a highwater mark for communication and intelligence.
edit another thought on why I used everything here, you are right I was vague and gesturing at like... everything but that really is the point, there is no intelligence without a fecund context in which to weave it together and that requires diversity in as many different axis as possible to increase the likelihood of it being possible in a given context.