Yes, I forgot to include it in the original comment, but besides frames and AJAX we also have static site generators, from no-code stuff like Frontpage all the

Yes, I forgot to include it in the original comment, but besides frames and AJAX we also have static site generators, from no-code stuff like Frontpage all the way to Hugo, and server-side templating like PHP, Jinja, etc. These are all solutions to the same problem: HTML lacks this natively. Web browsers had 20 years to provide a solution for literally copying text code and they were quicker to implement WebGL and web assembly... And the worst of all is that the only "templating" solution we got with <template> made the same mistake as frames did: the accessed page is the root and the included code is the children. HTML needs dependency inversion. Just like we include a single bundle.js that controls all pages in a website there should have been a way to include single template.html that defines the layout used through a site, the JS and CSS required by this layout, and other reusable template components too (which, imo, HTML should be to render without needing JS. Seriously, I should be able to write a web-component <my-h1> that unpacks to <div class="h1-wrapper"><h1> without needing JS because that cover 50% of the use cases...)