That's by design, since identifiers on Wikidata are not some kind of
top-down process where ever single actor's responsibility is defined
from the beginning.

This doesn't preclude good things from happening, as we've seen with LOC:
https://blogs.loc.gov/thesignal/2019/05/integrating-wikidata-at-the-library-of-congress/

I know that, but indeed that does not preclude deeper collaboration and synchronisation of Wikidata datas and other resources, and that’s the status of those potential collaboration and their maturity/workflow I’m interested in. Liking is useful of course but things happens also on Wikidata like data curation, duplicates entry identification on the external database working with their identifiers if it occurs that the same Wikidata item has two identifiers (for example : https://www.wikidata.org/wiki/Q539#P1015 has two values at the post time). I’m interested to know if this potential is exploited by some workflow authority control organisation by a periodic review/report of comparison of their datas against Wikidata community differences. And conversely if we imported datas from a datasource, if the changes made on the original live data source are reflected on the Wikidata datas.