WP is not the best option for big serious to them, but quite suitable for small.
From the point of view of seo:
- CNC able
- full customization, any meta tags, headings and anything - able
card make website possible
And to attract visitors to the site to gain links and behavioural factors - not the engine problem.
talking about bad code. It holivar, to start it.
In fact, if the site loaded quickly (on wp it is possible to achieve) - then it doesn't matter there OOP, mvc or indusScript.
There is still bad code boret SEO guru I do not know).
In summary - you can on WP.
The more that in his spare time.
And on opencart, prestashop, etc.
SEO directly from the engine depends.