This is really bad news for me, I thought there is certainly a way for meta tags, but I’m still trying to implement a basic JavaScript snippet for analytics (Not Google, Plausible). 
Publish now seems like a wrong choice for blog materials, without SEO and indexing.
I can’t even share the link, which seems so bad without the title and description. (Obsidian Publish. Powered by Obsidian Publish.) I pay for a service, but it has watermarks everywhere, in the website, in the graph, in the meta tags, everywhere. Feels like a free service honestly.