Local devs or local dev company? In which country? In Germany they just won't find one. There are few good devs and almost no good outsourcers. Way more in Ukraine and there is an established ecosystem - there are even "accelerators" and "incubators" for outsourcer companies. In the U.S.? Because U.S. companies will never do actual coding in the U.S. - they only have U.S. front offices. Many of these "local" companies are actually Ukrainian, with a few guys in the Valley and 500 in Kharkiv.

As for local devs, then well, of course reason is the same as why dev companies exist at all: clients don't know how to manage the project or properly hire devs.