Amazon’s core business is AWS, which is worth more than 60% of the market cap. Amazon’s advertising business generates half the profits of AWS and has even faster growth, so should be worth 30% of Amazon’s market cap. The only conclusion is that Wall Street considers Amazon’s e-commerce to be nearly worthless other than as a loss-leader for Ads, and it should thus not be considered their “core business”.
But iOS is 87% and rising for US teenagers, which explains iMessage being the dominant messaging platform in the US.