My assumption is that we are talking about the Editor adding multiple <span> elements to the HTML content when the user applies formatting styles to content, which includes multiple sibling block elements. This is needed, because inline formatting is applied via inline elements. Since inline elements cannot contain block elements, each block element receives an inline child with the specified inline formatting style.
Imagine the following scenario: a bold style or line-height or whatever style needs to be applied to the second half of a list item and the first half of the next list item. There is no other way to achieve this other than using two child elements, one for each list item. A similar logic is followed in other scenarios as well. Even if in certain cases it is possible to assign the style to a single parent element, the Editor is designed to work in the above described way, so that it uses the same algorithm in all cases.
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