Try reading the article. The bias affected fundraising, not voting.
Headers make the day. 😊🙌
I would say not doing what they promise costs them more in fundraising than what google is doing.
True, but every message delivered has a cumulative effect. If people are getting "D" messages, even thought they may not donate, it can have an effect on their voting. I'd guess that many weak-minded and uninformed people respond to an inbox full of "D" messages and a dearth of "R" messages. They could infer that the "D"s are a lot stronger party and deserve their vote. Remember, it's not the one single technique that tilts an election, but the combined effect of scores or hundreds of such techniques the D's deploy.