Imagine the following scenario. A law firm in a major city undertakes much work in media and intellectual property areas. Clients might be seeking to protect copyrights or attack them. The crucial point is that no other lawyers in the firm should be committed to organizations whose positions might make maintaining that independence difficult.
Suppose then some lawyers in the firm are acolytes of Landmark and might have even persuaded the law firm to subsidize their Landmark courses under the guise of continuing professional development.
Now imagine a client comes to the firm who is being threatened with a lawsuit by Landmark. Landmark is not a client of the firm. What then is the position of the firm with respect to taking on the client?
If the lawyers have disclosed their interests, the firm could say 'we can't accept this client.' But, as is likely, the (Landmark) lawyers haven't made any disclosures, then would the firm be in breach of conflicts' rules.
I suspect it could be since those lawyers would find themselves in a situation where to give the client zealous advocacy could be compromised by their adherence to the defendant organization.
Professional service firms--law, accounting, consulting--should audit their members' allegiances to external organization to prevent such conflicts coming down the pipeline. Or they could face potential malpractice lawsuits. At least, there are challenging ethical issues abounding.