There's a balance though, isn't there. They need to have some transferable skills and relevant experience. Have they been involved in organising or leadership within a council, a charity, a Union, an industry body, or even just a large company first? Do they know how to hold a meeting, how to question heads of department, how to disseminate large data sets, how to interpret legislation and policy documents, how to make complex decisions, how to manage multi-billion pound budgets, how to communicate to millions of people, how to deal with leading politicians of foreign states, how to negotiate with industry leaders, how to lead tens of thousands of staff? You need some transferable skills and experience. Otherwise they will be out of depth and become yes men who do whatever they're told, because they don't know what they're doing. Imagine a Rob Kenyon type meeting with a JD Vance type to negotiate a trade deal or discuss foreign policy. They would get outmanoeuvred with ease.
It's reasonable enough for a few backbench MPs to learn on the job, but there's 20+ cabinet positions that need people who know what they're doing. Reform currently have what, half a dozen or so competent candidates?