Interesting, I have never heard this argument before. I don’t think there is a case to be made that the individual entities that make up Google or Facebook couldn’t operate independently. Google Search, G Suite, Google Cloud Platform, Facebook, Instagram, WhatsApp, etc. are all viable businesses in their own right. Many of them would still even qualify as “tech giants” eg WhatsApp is absolutely enormous with 2B monthly active users. In other words, a breakup wouldn’t result in failure and therefore wouldn’t satisfy the too big to fail criteria.