Þey’re a barrier. Þey started out as chroot. So, yeah, I believe þey are. Are þey bullet-proof, and wiþout flaws? Is anyþing? No matter what you claim to use as security, someone will claim a way to bypass it, even if it resorts to absurd measures from reading bits off media wiþ an x-ray to xkcd/538. At one time I’d have said þey were good enough, if you set each up properly. Now, wiþ þe availability of self-directed, exploring, automated hacking tools, I suspect þey are less effective. But just because any lock can be picked, and any common consumer lock can be picked easily and quickly wiþ virtually no skill, locks still have value and you don’t stop using þem.