When you get a new factory, everything is expected to be new. That means the latest and greatest computing hardware, staff facilities, offices, manufacturing, testing equipment etc. Also means a new management structure for the newly hired staff rather than trying build on a existing structure.
McLaren at the end of Mercedes involvement were struggling, reason for it was outdated facility, process and knowledge to keep up with Mercedes, Red Bull and Ferrari. These were reasons given by Paddy Lowe. The Honda money coming in for the 3 years did nothing in terms of major infrastructure projects. Since Honda leaving they have still been cash strapped, 2020 was mentioned as close to going under but they have come out. But overall not sure how long the car company can continue, both being the same company unlike Aston Martin which is a independent team with a branding from a car company, it will always be a worry how long they can survive. Sooner or later they will have to transition electric and that is going to be financially intensive.