Probably because we're being told it is private and secure.
This is just the first six results when searching "best privacy browser 2023". And, all recommend brave. A few have it as number 1.
https://www.zdnet.com/article/best-browser-for-privacy/
https://nordvpn.com/blog/best-privacy-browser/
https://kinsta.com/blog/most-secure-browser/
https://www.privacytools.io/private-browser
https://surfshark.com/blog/what-is-the-best-browser-for-privacy