The problem is who gets to decide what is "core" to your business?
Look at airlines, once the McKinsey types were let loose it turned out none of the stuff we think is core is needed at an airline; no need for in-house staff, catering, baggage handling, check-in, maintenance or even [owning] any actual aircraft. So much easier to operate without all that stuff to look after!
Taken to the extreme presuambly one would end up with nothing but an airline's name and trademarks, a handful of overpaid management types, and maybe a bunch of lawyers to look after all the outsourcing/subcontracting and licencing deals.
