Have you done any experiment or read of any case study to check if too many tags are really damaging the SEO of a website?
Indexing pages with few text (like tags with just one article) is penalizing for the SEO?
The main issue with having too many tags is that CMS such as Wordpress or Blogger will create tag pages similar to category pages which can result to many similar thin content duplicate template pages which can negatively affect your SEO.
However if you are looking to insert many tags to improve the User experience then you can nofollow and noindex the tags pages which will not cause any SEO issues.
TIP: If you use wordpress there are plugins such as All in One SEO & Yoast which options to noindex these type of pages automatically.
According to the Google's Panda Update - Website must have quality content. Websites with low & thin quality content is getting low authority. It says:
Google’s Panda Update is a search filter introduced in February 2011 meant to stop sites with poor quality content from working their way into Google’s top search results. Panda is updated from time-to-time. When this happens, sites previously hit may escape, if they’ve made the right changes. Panda may also catch sites that escaped before. A refresh also means “false positives” might get released.
The following tags are important in SEO:
- Title Tags
- Meta Description Tags
- Heading Tags (H1-H6)
- Italic/Bold Tags
- Meta Keywords Tags
- Image Alt Attributes
- Nofollow Attributes
- Robots Meta Tag
- Schema Markup
- Social Media Meta Tags
- Viewport Meta Tag
Tags will help Search Engine to understand more about website & helps in improving the visibility of website.
Meanwhile unique H1 tag must be used in a page. We can use H2-H6 tags wherever necessary using secondary targeted keywords.
Your list of tags that are "important" for SEO is a load of hooey. Some of them aren't tags (the attributes). Some of them are completely ignored by search engines (meta keywords, social media tags). Some of them can be replaced with CSS and have the same SEO effects (bold, italic, headings). Some of them have the ability to change how your site looks in the search results but have no effect on rankings (meta description, schema). I'm not sure how that list helps answer the question anyway. Your first part seems relevant, but not the tag list. Oct 1, 2018 at 9:41