Why is chat strategically important? What is Alphabet's strategy?

They've only ever made substantial profit from ads, YouTube (which they acquired), and possibly Workspace or Cloud. The last time I looked at their filings, they weren't transparent about which businesses are profitable.

This isn't a company that's had a coherent identity or strategy.

iMessage is important to Apple because it's an exclusive social network that only Apple devices can access.

Slack is important because it's a backbone of a business SaaS ecosystem.

But Hangouts was never going to have either of these functions.