What I am curious why haven't we seen a quality mashup of a SE site? Some sort of interesting curation/filters etc. Even the new CC-share-alike allows commerci

What I am curious why haven't we seen a quality mashup of a SE site? Some sort of interesting curation/filters etc. Even the new CC-share-alike allows commercial mixins https://creativecommons.org/licenses/by-sa/4.0/ https://creativecommons.org/licenses/by-sa/4.0/ . So being that SE started with SO and thus heavy programming emphasis there should be a plethora of interesting mashups. Instead the only SE content derived sites have been banal copies.