It can do. Additionally, because each part is now smaller it's now easier to ensure that each part, in isolation, does what it says on the tin. It also means that other projects can reuse the parts. An example of the last point would be the Regex crate.

Regex is split into subcrates, one of which is regex-syntax: the parser. But that crate is also a dependency of over 150 other crates, including lalrpop, proptest, treesitter, and polars. So other projects have benefited from Regex being split up.