What's the benefit in using Schema.org markup as Google already knows all the information

Question

I was wondering if it was worth the effort of adding Schema.org markup to an existing local business website when it seems to me that Google already know most (if not all!) of the information I am marking up.

In the case of a local dentist Google already know:

• Name
• Opening hours
• Address
• Email address
• Telephone number
• The fact that it is a dentist
• I've added the logo at Google My Business

What's the point in adding more markup?

EDIT:

I probably should have stated what my concerns are:

1. Misunderstanding of the schema.org markup specification. There appear to be many questions on this website alone about it.
2. Making genuine syntax mistakes in the additional HTML markup.
3. Adding more markup complicates the HTML.
4. The additional knowledge that site editors need.
5. Will a CMS's WYSIWYG play nicely with the markup?
6. Keeping up with changes to the Schema.org specification.

I could really mess up Google's knowledge of my business if I make a mistake. So why take the risk when those smart Google algorithms do all this for me.

Answer 1

There is no boost in SERP placement as a result of using mark-up with one round-about exception. I will explain.

A page has mark-up and a search query makes a match against that page. Simply because the matched page has mark-up, one cannot assume there is a boost in SERP placement. That is not how it works and an overly simplistic view. There is no metric and/or algorithm that will boost a pages placement simply because a page has mark-up.

However, answers from the knowledge graph can influence trust for the match over others and early search query algorithms may place any match found from the knowledge graph over others. Mark-up is not necessarily a requirement for the knowledge graph since the knowledge graph predates mark-up, however, it is a tool for trusting the data from content. One requirement for inclusion into the knowledge graph is that the data is verifiable/corroborated in more than one trusted place. Please keep in mind that this is extremely early in the search query process. What has to be remembered is that are quite a few algorithms that influence SERP placement and can ultimately remove entries from the SERPs including filters that effect SERP level penalties. So again, mark-up in of itself does not influence SERP placement, however, matches from the knowledge graph that may be a result of mark-up may influence placement.

Pure and simple, mark-up is not available to all websites. For example, there is (last I looked anyway) no mark-up for whois and other network information. There are other examples primarily in the data presentation market. Mark-up is targeted to sites that can benefit most such as e-commerce, business, organizations, etc.

Be that as it may, mark-up is still a good idea. Mark-up is intended to communicate data directly to search engines in a way that can easily be understood without having to parsing pages. Parsers are difficult to write and can fail from time to time due to unseen exceptions. While Google has gotten it right for a long time without mark-up, mistakes are still made. I saw a few just yesterday! Mark-up is your opportunity to be unambiguous. It is wise to take the opportunity even if it does not appear to be needed.

Answer 2

It not only allows Google to know, but virtually all search engines to know what information you're providing. Google uses this for its "cards" when you make a search. You're basically specifying exactly what the information is that you're passing on to the search engine so there's no confusion on what is what. Google will favor you in search rankings if you do this.