It's difficult to take the author of the article being repudiated (Wingfield-Hayes) seriously when he has lived here for over 10 years and doesn't speak the language. Any other person who lived in a country for a decade and can't converse in the language would be (rightfully imo) shamed for it. Idk, say what you like about how journalists operate but living somewhere for a decade and not speaking the language doesn't…
In a company you will miss all the important things that are usually conveyed in casual French (this includes subtleties that change the meaning of a sentence).
Yes, people will speak English with you, usually fluently (and with plenty of errors), but this is not the language of choice for the off the record conversations.
Outside of work you will get by in supermarkets, but for more complicated shops your will have problems.
For the administration it is clear: without being fluent in French there is no way to do anything. Even if you are a native speaker you understand just half of it and hope for the best.
People in the street speak English [citation needed] but they will get tired after some time and then the English becomes unbearable.
Source: native French married to a foreigner who struggles to understand everything (not to mention the subtleties) after 15 years of active use of the language.