Meta tags on Blog, is it necessary ?

Should we put meta tags on the blog?. This question is still a debate among bloggers and SEO activists. In extreme would emerge two conclusions with a logical reason, that is agreed that if the meta tag is still required by the blog for easy keyword search engine spider detects put on blogs, and the second is the meta tag is no longer needed. 

First reason, Meta Tag still needs to put on the blog 

a. In the SEO guide book from Google (SEO guidelines issued by google there are said about the meta tag) 

b. In the search engine if you use specific keywords and have relevance to the keyword the homepage, it will display the meta tag descriptions of blog (note: if you do not put the meta tag will shown the beginning sentence on the latest posts on homepage) 

Example: 

Suppose that when typing the keyword "Computer Articles" if show the homepage , it will appear descriptions of  blog as shown: 

Computer Articles, Blogger Tutorials for Newbies, Internet, Computer, Windows Tricks, Modem Setting for Nokia, Ms. Excel, Ms. Word, Tricks of Blog, SEO, Online Business Guide 

(This description is attached in the meta tag). 

The above example indicates the meta tag is still considered by google. 

Second reason. Meta tags are not needed anymore 

a. Blog content is sometimes filled with a variety of keywords that are likely not related to the keywords meta tag attached so that keyword relevance and influence will certainly impact on the pagerank.

b. When google index the posts, it will automatically analyze the keywords contained in the next post title to check the relevance to the content of postings, the more relevant it will automatically word in the title of the posting will be used as keywords. 

This can be seen on google search results, for example, we typed keyword: 

"blogger tutorials for beginners" 

It will show the blog post title and the beginning of sentences relevant to the post title. 

So the final conclusion:

Meta tags still need to be put on a blog, meta tag more pronounced effect if the blog's content is varied (one topic).