The real question is whether the average publisher is better than an LLM at accurately classifying their content. My guess is, when it comes to categorization and summarization, an LLM is going to handily win. An easy test is: are publishers experts on topics they talk about? The truth of the internet is no, they're not usually.
The entire world of SEO hacks, blogspam, etc exists because publishers were the only source of truth that the search engine used to determine meaning and quality, which has created all the sorts of misaligned incentives that we've lived with for the past 25 years. At best there are some things publishers can provide as guidance for an LLM, social card, etc, but it can't be the only truth of the content.
Perhaps we will only really reach the promise of 'the semantic web' when we've adequately overcome the principal-agent problem of who gets to define the meaning of things on the web. My sense is that requires classifiers that are controlled by users.