The answer is very simply advertising and affiliate revenue. If you use Chrome instead of Edge, Google gets the money from their ad engine, and Microsoft gets nothing unless you actively use Bing.

Microsoft Rewards gets you used to using Bing, which can then serve you ads on your searches instead of Google, earning money for Microsoft while giving you tiny fractions of a cent in points as a gamification strategy.

Edge has shopping features that work just like Rakuten or Capital One Shopping, where if you "earn" cash back, Microsoft gets a cut of the sale.

Honestly, it doesn't bother me much. Edge has some pretty great features added in and it actually actively saves me some money and cuts me in where Google wouldn't. Plus, it somehow is less of a memory hog and feels snappier than Chrome.

It's a great browser and is a huge upgrade from Chrome from a performance perspective if you don't value their extra features and just turn them off. Not sure how Google took Chromium and made it run like shit wit Chrome when I feel like there isn't much extra underneath the hood.