Absolutely. It is a sad Catch-22 that many of the people who need help the most do not receive it because they do not help themselves, but their inability to help themselves is part of what they need help with in the first place.
Waiting for the inevitable arrest is obviously unsatisfactory, but I don't know how you can improve this process without trampling on rights.
As ideal as it may seem, people are wary of government having too much control over forcing people into mental health treatment. Unfortunately, as it turns out this is for good reason, because even in recent history there's been some pretty horrifying abuse of that power.
Oh yea of course, there are always cases that are clear black-and-white, but the same could be said about due process. If fifty people watch a guy stab someone to death, a police investigation and full trial probably isn't quite as necessary; that doesn't mean due process shouldn't exist, because the job of determining the boundary for "obviously guilty (or obviously insane, in the original example)" needs to have some formalism around it.
I'm not even saying that the government _shouldn't_ be involved in assessing mental health, just that people are wary of it for a good reason (in the same way that people are wary of any form of testing as a requirement for voting, because of the way that it was so horribly abused in the past).
Waiting for the inevitable arrest is obviously unsatisfactory, but I don't know how you can improve this process without trampling on rights.