When you embed a block that is part of a list, the visual elements of the list are visible in the embedded block.
They shouldn’t be, since they are irrelevant in the new context the block is embedded in, and don’t look good.
Embedded blocks could always be displayed as simple text, regardless of whether they are part of a list or not.
Something like this:
(This is how the embedded block is displayed when not part of a list.)
This is what would make block-embedding usable for me.