This is FUD. Neither Chrome nor Firefox are any good for *security*, as they both regularly get pwned at every hacking contest there is. Tor Browser is a different beast, because although it's based on Firefox, its attack surface is infinitely smaller than that of Firefox.
When running in Safest mode, it's essentially just rendering HTML/CSS/images: anything that involves convoluted decoding (video, webfonts, scripts) is disabled. Treating your web browser as an environment for declarative pages is best practice for security: no matter how many layers of sandboxing you'll use, people will find holes.
So apart from a few bypasses like the parent comment explained, TBB is decades ahead any other browser's security level out there (except for your favorite CLI browser over Tor which has roughly the same properties).