I was previously in the camp that people aught not to be saving web pages because I had a hard time imagining why someone would save an article instead of the peer-reviewed publication. But over the years I've come to realize Zotero can be used as a bookmark manager, and there are lots of articles and web pages that we want to save and annotate that have nothing to do with science, or similar topics.
I have run into many instances where being able to annotate the web page like we do for PDFs would be extremely helpful. So I totally support this feature request.
The request here is for the web library version of the PDF reader to allow annotation (which is fairly complicated and not a huge priority as I understand -- with a forthcoming android app, the vast majority of users will have annotation capabilities where they need them; I understand that's not the case of the OP, but software development always entails trade-offs on which features to prioritize). It's definitely planned, though.
HTML/ Web Snapshot annotations are a diffent topic, frequently requested (and actually used to exist way back). See e.g. https://forums.zotero.org/discussion/89301/feature-request-add-annotations-for-web-pages/p1 I'm not aware of any current plans in that area, but that doesn't mean they don't exist. It'd seem a fairly obvious thing to do, but getting it right -- especially to play nice with the existing PDF annotation feature -- is conceptually hard.
I use Zotero on a desktop, iPad, and Chromebook, depending on the task and my location. I suspect a significant number of people use it on a Chromebook, which is where the PDF annotation capability would come in really handy.
Personally, I'd put annotation of snapshots far down on the priority list. A snapshot can always be converted to a pdf, which can then be annotated.
I do wonder if some plugin could be developed to quickly convert snapshots to PDFs and begin annotating. Would this take care of the issue? It might be "good enough" for now. While printing html to pdfs doesn't always play nice, it's true that saving these as PDFs instead of html. Doesn't zotero rely on SingleFile? I rememeber troubleshooting some stuff with the singlefile developer who said that's what Zotero uses. I thought singlefile has an option for saving pages as PDFs anyway? Could that be added as an option to the zotero web connector?
As far as I know singlefile cannot save pages as PDFs. For me, one advantage of snapshots is that I can enable Dark Mode on websites by Dark Reader browser extension to reduce eyestrain and snapshots are also in dark mode. PDFs fail to do that, I use "Night for Zotero" Plugin to invert colors, but unfortunately the colors are also inverted on images.
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I have run into many instances where being able to annotate the web page like we do for PDFs would be extremely helpful. So I totally support this feature request.
HTML/ Web Snapshot annotations are a diffent topic, frequently requested (and actually used to exist way back). See e.g. https://forums.zotero.org/discussion/89301/feature-request-add-annotations-for-web-pages/p1 I'm not aware of any current plans in that area, but that doesn't mean they don't exist. It'd seem a fairly obvious thing to do, but getting it right -- especially to play nice with the existing PDF annotation feature -- is conceptually hard.
Personally, I'd put annotation of snapshots far down on the priority list. A snapshot can always be converted to a pdf, which can then be annotated.