Even though we have the option to "Apply assignees to all languages", there is no option to "Exclude all". This option makes sense for cases where you only need 1-2 languages and the rest should be excluded.
Example: For Bilingual Engineering, it's enough to look at only one language because the import rules are the same for all.
Other example: For Linguistic Review step, sometimes you only have to review 1-2 languages out of 20, so it's quicker to "Exclude all" and then only assign the required languages.