advantages of meta tag:

It’s believed to still be used by some lesser-known search engines. Having a meta description tag on each page may give those pages an SEO advantage with those search engines.
It appears in search results with some search engines, especially if it contains the keyword searched for. (Search engines sometimes display part of the meta description tag content along with a page snippet, or just a snippet, depending on the search engine and what is searched for.) Well-written description tags that appear with search results may be better at attracting searchers to the page than snippets of text from the page.
It may carry a little weight with Yahoo.
It may be a factor with some lesser-known search engines.
If you list misspellings of words that you use on the page, it may help your page appear in Yahoo search results for those misspelling.

Advantages of meta tags
Sometimes snippets are better at providing exactly what searchers are looking for than page summaries, especially if the page has a lot of content.
Time spent working on meta description tags is time taken away from working on page content, which is more important.
When you use it, you’re telling your competitors exactly what keywords you’re optimizing each page for. Competitors can take those lists that you carefully crafted and optimize their own sites for the same keywords.
Time spent working on meta keyword tags is time taken away from optimizing your site for those keywords, which is more important.

references:
https://www.webhostingtalk.com/blog/meta-tags-and-search-engine-optimization/