The UK prime minister's office is a hot potato. No one actually wants to be in a position where they have to make the hard decisions; they instead want to be in a position where they can criticize the decisions for being wrong (without having to offer any alternatives!).

Like the other reply says, nobody wants this job.

It’s difficult to remain neutral, but… there’s realistically no feasible way to deliver Brexit without medium-term economic damage, or alternatively accepting essentially all EU rules while having minimal influence on them. Few serious politicians wanted it, and they don’t want to step into a role where they have to deliver it. The idea seems to be to let her take the blame for the inevitable failure first.