Public and University libraries are also archives, but they follow strict guidelines to stay within the bounds of copyright law and fair use. There are limitations on how you can view the archived copyrighted material, limitations on how you can do so, etc. No one is claiming that "archives" are a bad thing, at least not that I've seen.

What I'm complaining about with IA specifically is that they're basically taking the MegaUpload approach of pretending that flagrant disregard for copyright law is totally fine, and then hiding behind vague data harboring laws and shouting "We're an archive so it's fine!!!!". Depending on how far you want to go, you can say that ThePirateBay or LimeTorrents is also an archive, but most people don't dispute that those sites are piracy.

If IA broke copyright law only in regards to something like AbandonWare, I wouldn't really be complaining, because that is something that should be archived and if it's truly abandonware then you're not even eating into potential profits, but that's not what's happening. Even the act of archiving copyrighted material that's still for sale is fine, but they should be operating within the bounds of the typical library archiving standards, which I don't think that they're doing.

As I said, if I'm aware of how easy it is to get pirated material on IA, then I'm quite confident that their staff is too.

Internet Archive is engaging in redistribution with flagrant disregard for the law, so it is not an archive despite what it says on the tin.

Note that preservation and redistribution are two very different things, there are very specific limitations to redistributing something you don't have explicit licensing or permissions for.

Further reading: https://www.law.cornell.edu/uscode/text/17/108