Well, it's already discussed in this thread, I do think
meta tags are important.
Of course it's not much in itself, and it's always better to have no meta tags at all than to have the same on all pages, but it's something that matters. Will not be really optimizing the SERPs because of the keywords, but more a general thing, a bit like page loading time.
It's after all a way to communicate with bots. I do not consider telling officially "you can index" is not something that can help, and when you add the category, you help bots. Not only because they will trust and follow what you say.
I mean, when a webmaster adds the index,follow link, it's clearly stating you are allowing indexing, we all know search engines will by default assume it's ok to do it, but still, there is some kind of a copyright problematic being it, fully solved by the index,follow meta tag.
Then, same with category, you take the responsibility to state it's PG13, or whatever, and this is for sure not totally insignificant to tell it. Obviously the same as for the index,follow tag, bots will do their own cooking to rate and evaluate a web site's content, but, I'm pretty sure the guy running the company do prefer shared responsibilities when it comes to output search results. They are linking to us after all, and are responsible for it.
These two points are not the one of greater effect, but still, I do think SE will be more and more about how to sort, rate and categorize web sites, and these helps out for it.
Then, the lang tag can really matter, as some time SE have some trouble figuring out the web site lang. It does occur, even with Google, and when it's the case, the meta lang tags helps out a lot.
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