Many companies, particularly new ones, need different numbers and types of employees in different phases. TSMC needs different people to build a fab than to run it. Software companies need lots of coders when they're starting, and more support and marketing types when their product is already written.
It might be, but not likely. Especially given both the examples you give make no sense.
TSMC keeps building new fabs all the time. 7 nm fab built ? Working with good yield ? Nice. Who is the best suited to improve yield when there are problems ? The people who built the fab. TSMC wants to build a unit in the US ? Who gets consulted to decide whether the US is good enough for it ? What resources should we look for in the location in the US for building 7 nm fab in the US as well ? The same people, who build the fab in the first place. Who is best suited to build the 5 nm fab ? While there may be some physics / nano engineering required that was not done for the 7 nm fab, who can help the best in not repeating the mistakes / inefficiencies that happened during the 7 nm fab ? The very same people.
Software companies ? Very similar, I'll be briefer here. The very same people who built the original code will know and understand what corners were cut in the original rush of delivering - and when the product cannot scale can directly to fix them. Any other person will have to work much harder to first understand the code, motivations that drove decisions, and then fix them while not knowing what else can be broken. Obviously detailed unit tests was one of the first corners to be cut :)