They are development specialists. They don't do website design because they recognize design is a whole other skill set and thus, industry.
They have a great point and this made me think about the website content clients we work with and what their experiences have been when updating their website design and website content.
Our Conclusion: don't bundle your content strategy and website content with website design and development - it's all separate. Find a specialist company - and preferably one who can also train your staff to manage the in-house marketing you need to do on a daily basis.
You want people who are dedicated to best practices in their field. Not those focused on trying to be a one-stop shop - usually this means doing an 'ok' job on all areas, rather than a professional, knowledge-based excellent final product.