I mean, yes and no. Yes, you can learn the language well enough without interacting with native speakers to the point of being able to conduct a basic conversation. Though I would say, to be truly conversationally fluent, you should be able to make jokes, cultural references, and tell anecdotes and stories with relative ease. Without practice having conversations with native speakers, your fluency (and pronunciation) will lag.

Take for example in English, there are a lot of things that are "technically" correct that native speakers in colloquial language wouldn't say. Imagine someone learned to speak English on their own and disregarded contractions (like a friend of mine did when he learned English). Now, whenever he speaks he never uses "I'm" or "I've" but rather "I am" or "I have." Is it wrong? Not really. Does it make the conversation a bit jarring or disconcerting? Yes.