One of the advantages of the Brave browser is that it has an ad blocker by default, which has made it gain popularity. Firefox allows you to install a third-party AdBlock, but if it came integrated it would be perfect for all users.
This would be good and would be the minimum expected of Mozilla to do considering their competition did it as early as Opera 8.0 (2005) back with its editable content blocking list. However, as Mozilla and their CEO get 90% of funding from Google itself, it's unlikely we'll see this development.
I want Adguard, which is an open-source extension with strong ad filtering capabilities, and has many built-in filters and instructions, and should integrate this one