Hi nice to meet you!
I have to say your response is, to me, ungrounded, and rather an arbitrary statement. Whyever should “META description and tags (be) meant to be added at the theme level or through a plugin”? I see no logical reason for this. Such metadata is not a theme- or plugin-related or dependent topic. Attributes such as description
are ubiquitous to all websites, search engines, CMSs, social sharing platforms, etc. Thus a website CMS should support basic metadata entry for users. Do for example Squarespace users need to install a third party app to write meta descriptions? No. Should they? Of course not.
The only thing I’ve been able to find so far is this article (https://codex.www.ads-software.com/Meta_Tags_in_WordPress), which is a rather obtuse treatment of meta attributes.
I get it, WordPress is free. But core meta attributes are a staple of the web and all users should be able to work with them without needing to install or buy additional, third party software (which is sometimes bloated, can cause other issues, etc.).
I dropped a feature request in https://core.trac.www.ads-software.com/; we’ll see how that goes.
Thanks for interfacing with me on this! All the best.