The CSS scoped is newer and poorly or not properly supported by browsers, technically. They do not limit the scope like they should according to the new spec. Now, browsers have supported this use of CSS nearly forever. The purpose of the placement where it’s at is to provide the widest compatibility with these as possible with themes. A large chuck of that CSS has been added over time to deal with mostly themes that have made some poor CSS decisions that not only negatively affect Connections but any other plug that output in the front end too.
As I continue to drop support for legacy browsers, older methods will be phased out.
I hope these replies have been helpful.