Because you have to support products, esp. antispam, while goog is generaly known for doing the other thing.
Uh, they literally paid MILLIONS for the antispam company POSTINI and thats what the original anti-spam features for GMAIL are based on... in the last 18 months or something, google apparently deleted that tech from their stack, I posted about this when I first started having so much spam inbox my gmail....
So yeah - THEY _supported_ the product by paying millions for it...
Then they did "the other thing"
And now in 2022 any gmailinbox is fn full of spam...