The easiest answer is that most tools and hardware in use predates those type of embeddings.

The advantage with block compression is that it is purpose built to minimize bits used, it's local to small blocks, decoding and encoding can be done with fairly simple code[0], and it doesn't require any specific AI hardware.

I am unfamiliar with NTC, but at first glance it seems to require an Nvidia card with RTX features, meaning it wouldn't be supported on Xbox One and PlayStation 4 (AMD GCN), Xbox Series X|S and PlayStation 5 (AMD RDNA2), nor the original Switch (Nvidia Tegra X1).

[0] https://learn.microsoft.com/en-us/windows/win32/direct3d11/b...