It can be. Providing the tool to do something illegal, with the sole purpose of the tool being to do something illegal, is illegal. Check out the YouTube DL project history/controversy.
Youtube-dl had a takedown because they specifically ran a circumvention in their tests. They removed the test and were restored.
Youtube-dl is still freely available.
Saving web pages is not illegal nor prohibited.
YouTube DL was alleged to be bypassing copyright protections which doesn’t apply to media without any protections like public web pages.
And in any case, it seems the software was reinstated by GitHub after The EFF intervened.