That's closer to mastery of a language than merely having 'learned' it. To me something like B1 is a much more important threshold, since it's the point where you start to be able to use a language in an uncontrolled environment. Obviously becoming more practised and fluent is important but to me that's a less important difference than being able to use the language for more than some predefined scenarios. If only because it allows you to learn unsupervised.

I don't know how the tests are structured and therefore what those levels mean in practice, but simply from the description on Wikipedia[1] I'd consider B2 quite enough of an achievement when it comes to learning a language:

  Can understand the main ideas of complex text on both concrete and abstract topics, including technical discussions in their field of specialisation.
  Can interact with a degree of fluency and spontaneity that makes regular interaction with native speakers quite possible without strain for either party.
  Can produce clear, detailed text on a wide range of subjects and explain a viewpoint on a topical issue giving the advantages and disadvantages of various options.

[1]https://en.wikipedia.org/wiki/Common_European_Framework_of_R... (also linked in the article)

It really depends on what your goals are with the language. If your goal is to "be able to communicate basic needs while visiting Paris for five days" then A2 is likely sufficient. If your goal is to "converse on a range of subjects with locals while living in France for a month" you're probably needing closer to a B2.

The French government considers B1/B2 sufficient to become a citizen.

I agree, and people should probably ignore advice from people who haven't reached it, unless they'd be content with being b2, which is a lower level than I think people realize.

This vastly overestimates the ability of many native speakers.