In my experience of speaking with Japanese natives to learn the Japanese language from the start. I had a belief that if I just had a pen pal or a Japanese friend they could just tell me if what I was saying was correct in their language.
Spoiler alert: I was wrong. One thing I absolutely thought would be a benefit really wasn't true. Well most friends will try their best just to do good by you but not all will tell you the truth. Now it really depends on your definition of what a friend is to you. But at the time my values weren't so great in choosing the right people. One thing to note is Japanese people or people really in general are courteous to your goals. They don't actually mean to lie they just want to make you feel better about yourself.
Another thing is they might not actually be good in their own language to give you accurate advice. This is a harsh reality also a touchy one because well you are learning their native language of course they should know more than you! But do they know it grammatically correct? or know enough just to get by in their own country? Be honest have you ever thought about that?
You probably didn't and its okay mistakes happen. There's also the aspect that they just want you to participate with them because of the lack of foreigner friends they have. Now these are just possibilities they aren't all necessarily true. But its something to consider.
If I'm going to learn something properly I need to qualify the person I'm learning from is giving me accurate information. It shouldn't be based off of where that person came from alone right? It's kind of silly to default pick someone off of that basis alone. I know in my own language I will skip or shorten things into abbreviations based off me knowing the other person can sum up what I was trying to say. But what about you? Would you know if it was a Japanese person talking with you in that same intent? Most likely not but this is the point being made. They wont think about that part. It's not like every Japanese person is a linguist waiting to explain everything they meant to you in conversation. It would be very foolish to think every person who was a Japanese native would do that service for you.
If anything I'm going to pay for my education and surround myself with people with the same beliefs and values. I'm looking for quality what are you looking for?