The manual is quite clear, so yes there is a warning. My best guess from reading these posts is the battery percentage is incorrect. What you may be seeing is something analogous to the software telling you there is 35 per cent of a battery that started with a 65 per cent charge.I guess that means that not everyone on the internet has read your posts.
There's too much victim blaming on this board. How would a new DJI customer know that their batteries need to be fully charged? Is there some kind of warning before you buy one? Is it on the box? No, well then DJI should replace it, fully charged before flight or not.
I've also never seen anything but anecdotal evidence that this is true. I know frank will come say, "Every time I see a post about a bird falling from the sky, they took off with less than 100% battery." Well, duh, most people take off and land multiple times per session. Odds are that most failures will hit people who have taken off with less than 100%.
To really know what is going on, the pilot should always be using a pre-flight check list no matter how many times it has flown. This should include checking the sensor readings for IMU and compass along with a battery check. I bet a look at the cells and the voltage would indicate it is not safe to fly.