At first, I was really mad about this. But then I realized, customers have a huge variance in expectation on sound, and the cost and size of adding decent on-phone DAC and amp is non-trivial. Many customers will be plenty happy with low-to-medium quality BT (SBC, ACC). Others will want high quality DAC and amp, so why not leave it off board and not make us pay twice for DAC+amp.
One can argue that a Note 10 is a flagship phone from a flagship brand, and can probably afford to put decent DAC and amp on the device; after all, they did so on all previous Notes. But even flagships have price targets, and if there is a trade-off between spending more money on a screen, cpu, memory vs audio, I can understand why they skipped audio.