I would say the first ever oil change is more about debris... the follow up changes will be more about recovering viscosity. The theory, at least from these YouTube guys (I never had a turbo engine before), are turbo engine is generating significantly more heat than naturally aspirated engine, hence they have accelerated degradation. I am sure Toyota engineer knows what they are doing, so I am uncertain about this huge gap between mechanics' recommendation and manufacturer' recommendation.
I heard this one claim, from Nissan senior executive, in one of their notorious class action that they claim the "life cycle" for the car is limited to what they recommend their car owner to perform maintenance schedule. In other word, once it gets outside the maintenance schedule, the auto company will consider the car is out of its life cycle. That is why every time we see these "lifetime warranty", they do not really mean lifetime in our definition. I am not sure whether Toyota is taking the same position. But I am sure they wouldn't say something like "LC can be expected to last at least to 300K miles"