There is a practical dimension here - if you don't tell them who you are, how can they identify (and delete) PII that belongs to you? "Please delete all my data" is a request that is impossible to comply with if they don't know who "me" is.
As for identification, the right to have the data deleted (where you have such a right which is by no means ...
You appear to be outraged and offended at the terribly dangerous technology in use,
but the database is filled with publicly-available data scraped from
sites like Facebook, Twitter, etc.
Publicly available data. You - and all of those other billion users - agreed to allow those platforms to publicly share your data with other platforms or scrapers ...