86. They create static HTML sites.
To be fair, that list is merely a list of bad things for SEO, and as such, items on that list can and are done not just by web designers and developers, but also by SEO consultants too, all too often.
Perhaps some web designers or developers who know a little about SEO, should also come up with a list of bad things for SEO which so-called SEO consultants have recommended for their client's sites too. I could start the ball rolling here...
1. Giving the client somebody else's sitemap, a sitemap for a completely different website, to load up to their site
2. Only understanding static HTML sites and asking the client to change static HTML pages, where the site is clearly a dynamic content managed site
3. Participating in link farms
4. Using blackhat SEO techniques
5. Asking for ftp access to the site to make changes, thus invalidating the warranty provided by the web developer (how can a web developer support a site if someone else can go in and make any changes to underlying code they want)
6. Selling to a client by jumping on the bandwagon and evangelising about the latest SEO technique in the hope that the client hasn't heard of it and thinks it's the latest miracle snake oil
7. Cold calling clients, going for a mass market client base and still convincing the client that they will do things on a personal custom basis rather than offering a budget run of the mill conveyor belt SEO service
8. Giving meaningless guarantees or tricking the client by giving guarantees that are meant to be misinterpreted
9. Providing tie-in SEO, that only has affect whilst the client is signed up, as soon as the client stops subscribing the ranking goes, because the SEO is just in the SEO consultant's link network
10. Telling the client their site's SEO is bad for reasons that have no affect on SEO
... etc ...