How was the vocabulary decided?
I'm very confused by how the Vietnamese course vocabulary is presented.
Currently at level 6, I've been introduced to words like "papaya", "bat", "kindergarten", "ferry", "ward" etc... Words that are fairly rare.
Yet, I still don't know very basic things like how to say any family members except mother, basic verbs such as: need, run, walk, talk, play, etc.., common food items, common greetings or departures, how to introduce myself or someone else etc...
By about level 5 in the 6 other courses I've done (2 accounts), I am familiar with at least: family members, greetings, very common verbs, common foods and basic adjectives.
In this course after many hours, I still can not hold a 10 second conversation, which has proven to be exceptionally useful IRL when learning a language, but I can tell someone "dơi ăn đu đủ".
So is there some sort of explanation as to why this course has avoids teaching basic useful things early on?
But it didn't do that. It was far too ambitious even there.
If you had wanted to teach the Vietnamese alphabet and tones, you'd have started a lot simpler. First with the letters themselves, and examples, then with tones having the listener learn to distinguish bạn from bàn from bán from bận, etc. That was never really done.
Use the tones. Those early lessons will be much more valuable to you if you can place the tone with what you hear.
Another thing to consider is that any language is tough at the beginner level. You have to get to pre-intermediate to start enjoying it. I'm about halfway through Vietnamese and I'm really enjoying it.
I think all experienced duolingo members can remember an insane/silly sentence from a language they were learning. "La scimmia legge un libro" is mine that I'll never forget from Italian. Sometimes absurdity is good for memory. I think you have a good point though, why not strive to teach pronunciation and practical vocab first? Why don't we approach teaching the language for use first--mastery will only come through dedicated studying and frankly duolingo isn't the place (as a sole resource) for that.