I think Artashes nailed it on the head. The blog is a supporting role, not the primary role of most websites. Many treat it as the star of the show, when really the website itself (individual pages) should be the star.
In SEO, we refer to it as "cornerstone content". The pages that are your primary focus get that designation.
You then have blogs, usually in the form of "evergreen content" - essentially content that doesn't go out of date quickly.
Next, you have normal blogs or newsletters, and knowledgebase type articles.
As far as length, Google's recommended minimum is 200 words per article. Heck, I've nearly got 200 words just in this post! Our own recommendation is 450 words or more. Doing the minimum gets you minimum results.
Do you need a 2000 word article, or even a 10,000? Only if it fits your demographic!
We have articles on our site that are mainly in the 500-700 word range, but we definitely have some that are over 1,000 and some over 3,000. Again, the type of user that we're targeting is very different. If we're discussing the advantages of the Google Tag Manager, then sure, 400 words is not a problem. If we're providing steps to integrate it, configure, and enhance, then we could easily exceed 1,000 or 2,000 characters. But we're targeting two very different types of users.
There's a definite SEO value to blogs and content, but they need to be used to support your product or website. If I create a blog about how to change the headlights of a 2000 Dodge Durango (which is a pain the butt!!!), that's not going to be a whole lot of a value if I put it on a web design type website. If I create an article about the Top 5 most exploited plugins in WordPress, that's a whole lot more useful to our existing user base (mainly WordPress users), but probably not the information we would want to share if we're trying to convince people to use the software. Showcasing the top 3 security plugins to keep your website up to date so you avoid plugin compromise - well then, we've got a whole different type of client we're talking to.