It is cheap insurance. You do not want bolts holding your suspension together to back out. That's not good.

Well, … every time I acquire a new car, … or new to me car, I always get an official factory service manual [… that started with my 1966 Ford Meteor, … all the way to my current two ‘10 Hondas.] And for the life of me, I can’t recall that any of those manuals ever called for a thread locker liquid to be applied to, … say, suspension bolts and nuts. Torque specs, … yes, every time, but no thread lockers! fwiw

F.S.

Definitely not brake bolts. I've never used it on my suspension and never had problems. My mechanics didn't either. I've never seen a repair manual specify to use it either. There was a couple of bolts where it was critical for them not to back off ( axle nut, and possibly a ball joint), but they had castellated nuts and cotter pins to secure them.