I completely disagree, and this is due to the thousands of people "designing" Web sites who all have their own opinion. You want to have the prospective client contact a "digital marketing agency". I'm guessing because that's with whom you work.

It's not about contacting a specific "type" of company. It's a matter of the prospective client making "well-informed" decisions on "who" will be contracted for the design, development and SEO. The only way to make that "well-informed" decision is to "vet" as many developers as possible in order to find out how long they have been developing, their experience and what services they offer. Of course price plays a huge part in the decision for most prospective clients. Often times, the developer with a higher hourly rate is much faster and experienced than someone charging much less per hour. Hence, the expensive developer will have an overall price that is less than the overall price of the developer with a less expensive hourly rate.

The Web development industry, meaning, those who are "professional" Web developers, has been overrun by too many "hit-and-run" developers which has left prospective clients confused, irritated and many times looking for "pay-back". It's time for all developers to be honest, speak kindly of other developers, and stand up for other developers whether you like their methods or not.

So if you are even considering stating the "type" of business to hire, please make sure to respect the fact that there are high-quality, professional Web developers who know at least as much as any other in the business - regardless of the "type" of business under which they operate.

That said, I do agree that there is no "one" element of a Web site that is "most important". If the site doesn't have all elements targeted, the site is going to fail in one way or another.