It is different, precisely because the end result is not the same - one broadly benefits the public while the other doesn't.

Substitute almost any disruptive public service to see the issue with your line of reasoning. For example - you seem to think that [ bulldozing private property ] to "construct an emergency fire break" is somehow different than [ bulldozing private property ] for any other reason.

Never mind that the sort of scraping being objected to is actually harmful to service health while what the wayback machine does is almost entirely unnoticeable.

The minuscule traffic generated by the wayback machine, which serves to preserve the content for years to come, is completely incomparable to the scrapers that hammer every single href linked on a website.

I'm guessing you use search engines, right? Those use scrapers and have to use scrapers. It's how they work.

A "scraper" is simply an automated process that fetches URLs intended for display to a human, and processes it. The act of scraping doesn't imply anything about:

1. The frequency of the fetches,

2. The way that the resulting page is processed.

Search engines scrape. Again, they have to. Same goes for archive.org.

Thing is, there aren't tens of thousands of search engines/archive.orgs that can overload a site at once.