Writing something like this would be a pretty big project, at least a few solid weeks of work for someone who knew what they were doing, and there's a lot of edge cases.
Usually anti-bot measures are in place for a reason, either to protect some paywalled content from scraping, or to prevent bots from getting at forms and causing a mess.
Few webmasters have cloudflare (or similar) anti-bot measures turned up higher than it needs to be (because it 100% will annoy people), and content that isn't a high-value target for blackhat bot activity is rarely difficult to crawl.
wget --mirror --convert-links --adjust-extension --page-requisites --no-parent https://site-to-download.com
So not sure what you mean by there are no tools available to mirror a website.
[0] https://chrome.google.com/webstore/detail/singlefile/mpiodij...
[1] https://chrome.google.com/webstore/detail/singlefilez/offkdf...