That's slightly unfair. A web designer (what we're discussing here) will do just that -
design the website. Any decent web designer will take the correct elements from the copy text (
provided by the client) for the all important page titles, descriptions, headings etc. and structure it correctly for SEO purposes.
What they won't do is write the content for you, track (or even check) your SEO results, and manage your digital marketing strategy. You'll want a digital agency for that, who'll charge you £££ (per month) but for that they'll do very little but give you nicely formatted reports every month.
Step 1: get a moz.com paid account.
Step 2: Call yourself an SEO expert.
Step 3: Find gullible fools, and generate nice long, meaningless reports for them on a monthly basis while doing nothing of any real value
Maybe a bit harsh...but I've seen it myself countless times. Nobody knows your business better than you, if you can then write good copy yourself, or work with a freelance copywriter to produce good content in the first place.
When I build websites for clients I tell them from the start - they provide all content (text and photos). If they can't do that, I have professional photographers and copywriters I can put them in contact with (they deal with them directly), and maybe use stock images if they can't get anything else.