What’s in it for Google?
And the more complicated and difficult Gmail makes it for companies to access your inbox via open tech like email, the more likely it is you'll be forced to pay for Gmail Ads.
The bonus is Google gets to couch this as being "for the users." Gmail already has fantastic spam filtering and it's highly likely they use all this stuff as spam signals already. I would be very very careful of any claims from a giant advertising monopoly that this is "for the good of all."