I think the idea is that CeMAS is monitoring those channels and associates potential crimes with accounts. They can make a criminal referral to the police that a crime may have been committed, but they may not be able to find out the person's actual name or persona from their account or other public information.

But it would be easy for Telegram to just hand out the telephone number, and in the majority of cases, the number would be registered to the offender. We're mostly talking about unsophisticated offenders here, people agitating for hate, neonazis, unsophisticated child abusers...