Should you delete old blogposts?

I use a blog on my business website.
I write about 2 articles/week.
I started this in 2012.
Some of these articles have just 100-200 words and don't receive very much search engine traffic.

Should I keep my old blogposts?

I was thinking to create a page about a certain topic and merge all the old posts on that page.

Example:
I have 10 old articles/blogposts about social media.
I create 1 new page about social media.
I copy the content of the 10 articles on the new page.
I redirect the old articles to the new page.
I now have a 4000 word page about social media.

Good idea/bad idea for SEO?
What do you think?

If it ain't broke, don't fix it. Playing with old URL's is the easy way to go broke and lose all the leftover traffic. Even if you merge them, it simply won't make any sense to the visitors. No one's going to sit and read a 4000 word article unless it's some sort of tutorial or a deep research on a certain topic. Keep those old blog posts as it is.

I Agree with FBGuru, according to some Google specialists "Old is Gold" so you can make new pages while you keep the old once intact and they'll bring more value to your blog.

I agree- If it ain't broke, don't fix it.

No never! The number of indexed pages on a website is a factor which contributes to a websites authority.. Also if you have backlinks you are going to lose link juice and ultimately your ranking on some keywords may suffer.... So for me I would never delete any old content - the exception being if I had a ton of spammy links wrt -ve seo... in which case it might be worth a try to remove those pages with a redirect to another domain versus disavowing links which is in my opinion is the very last resort to sorting that type of mess...

some of the best advises on basic SEO that I can get around so far. Appreciated.