WooCommerce: Single-product-postslug template not working?

First,I know wordpress won't allow you to use template for posts (WooCommerce's product page is built via post). So I look for the Template Hierarchy. It says there:

single-{post-type}-{slug}.php (Since 4.4). First, WordPress looks for a template for the specific post.

For example, if post type is product and the post slug is dmc-12, WordPress would look for single-product-dmc-12.php.

single-{post-type}.php – If the post type is product, WordPress would look for single-product.php.
single.php – WordPress then falls back to single.php.
singular.php – Then it falls back to singular.php.
index.php – Finally, as mentioned above, WordPress ultimately falls back to index.php.

So I created a template and name it single-product-ccc(ccc is one of my product's slug name), but nothing happened, nothing was affected.
But by creating a template named single-product will affect all of the product pages.

Why is that happening?

I don't get it. Even a single-2313.php (2313 is one post's id) will overwrite the default single.php for that 2313 post.

Why single-product-slug is not working in the same way?

Thanks.

via Chebli Mohamed