This is the idea behind Esperanto, the movement behind which further stipulates that the common second tongue should be universally second, to avoid privileging native speakers and promulgating hegemony. (Granted, Esperanto vocabulary and orthography is quite Euro-centric.)
Learning a second language is difficult, especially one very unlike your native tongue. Native speakers of the de facto lingua franca always have a first-order advantage.
Language is more like a virus than like a system. People will speak whatever language to which they are exposed. If it enables them to express most of the information they need to express, they will expose others to that language (reproduction) and tweak it on their own to be more expressive (mutation). This implies that it doesn't matter which language is "better" according to some technical or moral metric we might construct, it only matters which language can reproduce and mutate the fastest.
To make an analogy that the Hacker News crowd will appreciate: English is the C to Esperanto's Scheme. C as initially conceived was just good enough to write Unix and thus reproduce itself further, mutating along the way until it was simultaneously everywhere and unrecognizable. Scheme is beautiful and powerful and yet still mostly confined to textbooks.
English is actually fulfilling the original goal of Esperanto:
> Zamenhof's goal was to create an easy and flexible language that would serve as a universal second language to foster peace and international understanding.
We should be amazed at the global convergence on a language, even if it's not Esperanto, and it can accomplish all the same things.
The problem about Esperanto (aside from Eurocentrism) is that it has no real bulkhead to start from, unlike (to pick Esperanto-origin-era competitors) say French, English or Spanish.
Two other problems: 1) it's eclectic (i.e. its vocabulary is assembled using words belonging to other European languages), and 2) unlike English, it uses diacritics.
> the movement behind which further stipulates that the common second tongue should be universally second
The Esperanto movement does not strictly stipulate that. The phenomenon of denaskuloj, i.e. native Esperanto speakers (children born to parents who use Esperanto as their home language) is something that the Esperanto movement has been proud of for many decades now. Now, these native speakers might not get that much “privilege”, just some higher level of respect, but still, during my time in the Esperanto movement, I saw on various occasions grammatical disputes presented to a denaskulo in order to provide a "decisive" answer. If Esperanto scaled instead of remaining its niche pastime, it is easy to imagine first-language speakers of the language gradually being taken more seriously than second-language learners.
Learning a second language is difficult, especially one very unlike your native tongue. Native speakers of the de facto lingua franca always have a first-order advantage.