But if you serialize the DOM as-is, you literally get what you see on the page when you archive it. Nothing about it is dynamic, and there is no sessions nor credentials to handle. Granted, it's a static copy of a specific single page.
If you need more than that, then WARC is probably the best. For my measly needs of just preserving exactly what I see, serializing the DOM and saving the result seems to do just fine.
Yes you save something that's mildly better than print-page-to-PDF. But it still misses things and the interactive stuff is very much part of 'exactly what I see'. Like, a random article with an interactive graph, for instance - like this recent HN hit https://ciechanow.ski/airfoil/
It's not that there aren't workarounds, it's that they are clunky and 'you can't actually save the most common computery entity you deal with' is just a strange state of affairs we've somehow Stockholmed ourselves to.
If you need more than that, then WARC is probably the best. For my measly needs of just preserving exactly what I see, serializing the DOM and saving the result seems to do just fine.