If a web designer or a developer has knowledge of On Page and Technical SEO s/he can design a website by following the SEO rules. Search engines rank pages with good On Page SEO (Title Optimisation, Meta Description, Image Optimisation, Good Navigation, Proper URL Structure, etc.).
Save time by incorporating On Page SEO factors while at the development stage itself. Except for placing keywords (Keyword Analysis required), we can do the remaining On Page SEO activities during development, if the developer knows the SEO rules.
We can avoid changing web pages and uploading into the server as it also takes more time (for changing files from server one needs knowledge of FTP or hosting).
Good On Page SEO with Responsive Website is a factor for ranking in SERP. Mobilegeddon algorithm checks all pages of the website for its responsiveness.
Having knowledge of multidomain skills is very important as one can avoid dependency and save time. Web Designer with SEO is a more demanding skill in the online marketing domain.
Maximum number of companies hire web Designers / UI Developers / Web Developers who possess web design skills with SEO knowledge; specially web page optimization skills.
A Web Designer can learn On Page SEO quickly because it depends on coding (HTML) and optimising content with proper heading tags. Image optimisation with the help of ALT tag, internal linking within the website, minifying (HTML, CSS, JS) files, etc.