I get most my business via Facebook posts looking for web development services. Usually they are in blog groups and mothers groups. Usually I, along with a few other web developers will link our websites and offer our services.
Without fail, many people suggest that the original poster use Wix.

“It’s so easy. Just do it yourself!”

Yes, it is easy. Unfortunately that means that the code that get’s generated is very very bloated.

Bloated code, why is that even a bad thing?

Google likes clean code. You have a much higher chance of having your content indexed properly if the markup makes sense. Google isn’t going to look at the render all the time. Why should it when they can rely on compliant markup? If Google isn’t going to like it, chances are you aren’t going to rank no matter what you throw at it. Yoast can only do so much.
Content is key. Markup alone isn’t going to help you rank. I highly recommend those who are serious about SEO get a copy writer who understand keywords and SEO.

Prove it, Show us how bad it is

So, instead of just telling people it is bad, I decided to take a wix template and write my own markup and styles for it.

Their Version

URL:
http://www.wix.com/demone2/exotic-pet-shop

Source Code:
You can see this if you use chrome, right click and choose inspect element. Wix uses javascript so simply viewing the source isn’t going to show the rendered markup. I have created a PDF of the source code. It is 40 pages long!
Wix source Code

Screenshot:

My Version

Most of the fonts used were google free fonts. They had used one font that I would need to pay for. I used the closest google one I could find.
URL:
http://mobiusweb.com.au/wix/

Source Code:
You can view source on the above link. Alternatively I have saved it as a pdf. It is only 1 and a half pages long.
My Source Code

Screenshot:

Hope this helps.