No matter if we learn from the streets, study a language in University, or learn as an infant from our parents, we all learn grammar. It’s impossible not to. Some people don’t need to put as much effort into studying grammar from a book or from a teacher — they might be able to pick it up more naturally from conversations, tv etc. — but they are still learning grammar.

Well... This is complex, i think it really depends on the person and the language, you know? I'm a native spanish speaker and I learned english listening to music, watching movies and tv shows, etc. I never really look up for grammar or anything however it has its pros and cons, the con is that I STRUGGLE sometimes when I'm writting something, I can understand pretty much everything, but I'm lacking skills when I'm writting (and sometimes speaking) something.

Nope, well it might be right in some languages, but for ex: "arabic" is a hard language and there are a lot of grammar rules that you absolutly should know and without them you can will be making a lot of mistakes in your pronounciation and at writing as well, As an arabic native speaker I don't really believe that learning a language without studying grammar can make you a good speaker in that foriegn lang that you're learning , but I guess or maybe in english you can learn this one without studying the grammar side hardly, so you can learn this one by practicing saying different idioms and common phrases every day so you've already applying grammar rukes through your speaking and even in writing, so that's basicly what I'm thinkjng, I wish I could help you with my answer.

A Big YES❗

Can you live without breathing? The same applies to learning a language without learning grammatical structures.