My belief is that no one at IB spends any meaningful amount of time on the FT mobile site as a user, i.e. looking for travel info/discussions, doing searches, and actively participating on a daily or near-daily basis. Or if they do, they don't apparently care about reading the information that has been organized in wikis, or advanced thread searches, or anything else that requires being at the top of a thread.

Because the alternative is that a frequent user of the FT mobile skin puts up with all of this on a daily basis and thinks to themselves "yup, nothing at all wrong with this experience! Great job folks!" and thinks this is awesome UX.