I think I can help you with this question, so I’m going to do my best to answer it now.
Content Marketing vs. Blogging

For starters, let’s not mix up blogging with content marketing.
You’ll definitely find SEO agencies that publish blog posts to a site as part of their package. Yes, they’ll focus on link building, content optimization, and publishing content to a site.
We cannot confuse content marketing with blogging.
Content marketing is a multilayer approach to building an audience and generating leads.
Blogging is a lot different since it just consists of daily, weekly, or biweekly publishing of a blog post on a website. There really isn’t much to it other than sharing posts with the world on your blog.
And as you should be aware, blogging doesn’t consist of a deeper strategy like the hub and spoke model of content marketing.
The Difference between Blogging and Content Marketing
In the early stages of content marketing, you identify customers’ needs and wants, things that they are interested in, buyer types, and start developing content specifically tailored to their ideal target audience.
On the other hand, blogging does none of this. It has no promotional strategy involved whatsoever. And the cold hard truth is that an SEO agency probably can’t be good at everything.

Examples of SEO Strengths & Weaknesses
Example: an SEO agency is phenomenal at link building. But they might not be at Onsite technical stuff.
Example: an SEO agency is great at Onsite technical stuff but they aren’t good at true content marketing.
Advice for SEO Agencies
First and foremost, if you are an SEO agency and you want to offer content marketing services, please remember that the customer always comes first.
So, do a deep dive into what content marketing really is. You have to learn how it works and know what the key components are. Then you can start to hire people that fit the right profile.
Before attempting this with clients, try it out for yourself on your own website.

Hiring a Content Marketing Team
Once you start getting a grasp of what to look for pertaining to content marketing, you can start hiring and building a team and then offer your services.
Don’t mix up blogging with content marketing.
We took this path in my SEO agency.
My company strictly started off as an SEO agency and we realized the real power that good content marketing could have on an SEO campaign.
Content marketing is so authoritative that it gave us 10 times the firepower in our SEO arsenal.
When you are creating content that generates links, builds an email list, and generates traffic on its own, client satisfaction figuratively goes through the roof. You’re going to have very happy clients in this scenario.
And it’s so much more than client satisfaction. The quality metrics of your site also go sky high. And you’re generating links, your domain authority is going higher, and everything is working really, really well.
Your actual SEO activities compound the effects of content marketing and make them that much stronger.

Approach This One Step at a Time
Yes, you have to take things one step at a time.
If you plan to offer blogging services, there’s a place for increasing the size of your site, and increasing the internal linking of your site. And there’s absolutely nothing wrong with just blogging as long as you do it correctly.
On the other hand…
If you plan to offer content marketing, make sure you have a content manager on hand, you’ve got some really good content writers, you have a content editor on hand that can make sure everything looks clean, you have a graphic designer that can make images pop and look good, and your articles need good formatting.
And talking about articles, they need to be easily skimmed, and the longer the article is, the more likely it is that it’s good. So, never discount the value of long form articles.
Using Your SEO Chops
And this is where things get interesting, because you get to use your SEO chops on the backend.
Many content marketers are really great at the content portion, but they aren’t so good at promoting their content.
As a search engine optimization expert that specializes in something like high quality link building, not private blog network (PBN) stuff, you have a leg up on most content marketers because they don’t have the chops to drive good link building like most SEO marketers do.

You can potentially offer the best of both worlds to your clients if you use all of your resources to the fullest.
That’s about it. I hope this helped.
If you have any other questions, you can always contact me here.
Thanks for reading.
Good luck!