Too much is being made of English first language as a reason for the Beatles' international popularity. First of all, the Beatles became wildly popular in countries like Japan where almost no English is spoken. Had John not been killed and had the Beatles gotten back together for a tour in their primes, they would have sold out large venues in many countries where the majority of fans do not speak any English at all. The chief reason for their popularity wide and far is immense musical talent. Ditto with the Rolling Stones.
As to the question of whether an obscure but similarly talented French or Spanish or other non-ENGLISH first language musical band was not discovered because of the language barrier, I simply do not believe this. Someone else noted the example of Abba- if a band shows promise to make money in their own language, someone will sell them the idea to do an English language album. Where money is to be made, it is generally not in human nature that smart people leave it on the table. There have not been any such megatalented non English bands that failed to rise to prominence due to not performing in English or being poor or obscure- talent is usually found and ridden to the bank if shows promise, in the arts as in sports. The Beatles and Rolling Stones were isolated instances of several talented persons combining in one band to produce internationally famous music that has been repeatedly covered in MANY languages by many artists. It's a talent issue, not a language issue, as to the reason for their success. Talent such as was possessed by the Beatles and Rolling Stones is less than generational, it's more like centennial type talent that comes around once every 100 years. It just happened to happen at the same time in the 1960s that those two bands emerged. Sort of like DaVinci and Michelangelo being somewhat contemporaneous.
The Beatles also had a rare gift for making musical chemistry and timing seem easy. I have been told by professional musicians that a lot of their music is hard to play right because of the beats and timing, and Ringo Starr is cited as being a really, really good drummer who could adapt his beats to songs as needed in ways that are not so easy to do. Professional musicians also refer to something called "musicality" - a professional keyboardist who once played with Prince said he had it in spades. So did the Beatles.
