Earlier quoted context omitted.
It does do archiving, and it does it very well. It's fast, provides short URLs, blocks ads in the archived pages, tries to bypass paywalls and login walls, and resists censorship. That's why people use it. And it's funded by ads, so yes, it does have tracking scripts, just like a good chunk of the internet. If you are privacy-conscious (or just don't like ads), then you can use uBlock Origin to get rid of them.
So it blocks ads making the content producer money, then puts in some ads of its own along with trackers. This is good because?
Two reasons. One is that ads probably aren't worth archiving, and removing the bloat makes the service run smoother (and it's easier to block the archive.today ads, than it is to block all those popups, random redirects, etc.).
The other is that "content producers" aren't necessarily good guys. Depriving all those clickbait manufacturers of clicks when you are hate-reading them is probably a good things.