Almost true. In most cases of stalking, you're right, because there is no evidence of mental illness.
To your point--no psychiatrist will institutionalize someone on your testimony, but a judge might. Depending on the state, a judge can send a person on a 72-hour court order to a psychiatric facility on the basis of an affidavit from a concerned party. If you can convince the judge, which in my state is apparently not difficult, the person wins a psychiatric admission.
I would receive advice from someone who has dealt with these issues before even thinking about such a course of advice.
"Lock em up!" feels like a great idea. Until you wonder what happens between them hearing about it, and showing up in court. Or after they are released from the psychiatric admission.
> No legal procedures exist to put down a stalker until after an actual crime has been committed.
That's not really true without jurisdiction filter on the assertion: there are jurisdictions in which harassment itself is a crime (in all circumstances, not just for protected categories or e.g. in the workplace). For instance, the UK with the Protection from Harassment Act 1997.
