Effect of HTML standard DIV + CSS layout on SEO

Two days ago, I published the article "SEO reference: DIV + CSS three rows and two columns of classic layout". Many friends asked me on MSN what role does the XHTML standard DIV + CSS layout play for SEO. These two days are briefly summarized and written for reference.
For XHTML technical issues, please refer to the relevant website research. The following describes the impact on SEO.
Simplified code
Using DIV + CSS layout, the page code is simplified, and I believe I know all about XHTML. There are two direct benefits of code streamlining: first, improving spider crawling efficiency and crawling a complete page in the shortest time, which has certain benefits for the indexing quality; second, because of its high-efficiency crawling capability, it will be liked by spider. This will benefit the number of indexed items.
Table nesting
Many SEOer said in its article that search engines generally do not crawl nesting of tables on three or more layers, which is not officially confirmed by search engines. The results of my experiments are not complete, but according to the current situation, when spider crawls the Table layout page and encounters multi-layer Table nesting, the nested content is skipped or the whole page is abandoned directly.
When using Table layout, you have to apply multiple tables to achieve a certain visual effect. If the nested table contains the core content, the spider skips this section and does not capture the core of the page. This page becomes a similar page. Too many similar pages on the website will affect the ranking and domain name trust.
However, there is basically no such problem in the layout of DIV + CSS. Technically, XHTML does not require too many nesting when controlling styles.
Although this is not confirmed, we recommend that you do not use multi-layer Table nesting during design. This is explained in the article by SEOer, I believe they are not without justification.
Speed problems
Compared with the Table layout, the DIV + CSS layout reduces the page code and greatly improves the loading speed, which is very advantageous for spider crawling. Too many page code may cause crawling timeout, and spider will think that this page cannot be accessed, affecting the indexing and weight.
On the other hand, the real SEOer is not just for indexing and ranking, but the rapid response speed is the basis for improving the user experience, which is very beneficial to the entire search engine optimization and marketing.
Influence on rankings
Based on the XTHML standard DIV + CSS layout, after the design is generally completed, it will be as perfect as possible to pass W3C verification. Up to now, no search engine indicates that the ranking rules will tend to comply with W3C standards for websites or pages, but it turns out that the ranking of websites using XTHML architecture is generally good. This may be controversial,