Maybe not the main tool for Hitler to reach his position as Fürer but it was certainly one of the main tools to keep him in power.
I understand and agree with what you were probably trying to say ;)
Yes, every regime is trying to get information about who's trying to destroy it. But (1) it's not a tool to get to power as much as a tool to hold to power, and (2) it's not inherently evil: if you have some regime that you actually like and don't want to see violently overthrown, you would support such measures, implemented in a reasonable way (!), too.