The goal is to preserve privacy by default--no extensions required. The vast number of users don't install them or wouldn't know which ones to install.
Brave is secure out of the box and doesn't require extensions to protect your privacy: https://brave.com/features/
Safari also doesn't require extensions to protect your privacy: WebKit Tracking Prevention Policy—https://webkit.org/tracking-prevention-policy/
Apple first shipped Intelligent Tracking Prevention in June 2017, long before Firefox or any other browser had anything similar: https://webkit.org/blog/7675/intelligent-tracking-prevention...