Website owners can request their site be blacklisted for archival, so this doesn't work for all websites.

Archive.today is another popular site that doesn't respond to blacklist requests.

Yeah this is true, but it works for enough websites to be a meaningful option, and it is almost always going to work better than something you have home-rolled (unless your core product is a direct competitor or something, in which case all bets are off ;))

A good is example of this is Pinboard which claims to offer website archiving. A friend has over 100,000 links saved (with an archival account) there. When we spent a few minutes looking at the archive links for those items a few weeks ago, we couldn't find a single correct, working, accessible archive from the most recently archived links (listed as archived 5 weeks ago, so also not up to date).

I wonder if Firefox "reader mode as a utility" might be a viable alternative for Pinboard like "content oriented" archiving?

https://github.com/mozilla/readability