ack and ag (the_silver_searcher) are two distinct tools. The latter automatically excludes .gitignored and binary files, just like ripgrep. In fact, it seems ag inspired ripgrep's behavior; in the blog post[0] introducing Ripgrep, BurntSushi specifically highlights that rg aims for the usability of ag:
> I will introduce a new command line search tool, ripgrep, that combines the usability of The Silver Searcher [ag] …