The scientific theory of carbon offsets is sound. The problem isn't in the idea of them, it's in the execution, which is either backed up (or not) by governments. The governments are in the pockets of Big Oil, so they don't enforce these agreements. Every time a corporation claims it's going to offset its carbon and doesn't, that's obviously fraud, and an executive should go to prison for it. And equally, the corporation should be fined more than it made through sales which would not have occurred without the fraud. Anything less is not a deterrent. The government creates the corporations (it grants them a charter, without which they do not exist) and then it fails to enforce their behavior.
It is still better to have carbon taxes instead and spend the proceeds on bioremediation including carbon fixing. But they would just have loopholes for the taxes, because the root problem is crony capitalism.