Stack Exchange started a while ago to add the most-used tag at the front of the HTML title to prevent scrapers from being ranked higher on Google than the SE site itself.
This makes a lot of sense for Stack Overflow, where the most important search term is often the programming language, and this search term is very often only present in form of a tag, and completely omitted in the actual question title. So you get titles like
python - How do I do X?
This addition improves SEO a lot as the programming language is an important search term most of the time, and it is often omitted in the question titles. The same goes for game names on Gaming.SE, where adding the tag to the title is critical for SEO.
But is the basic assumption behind this feature valid on other SE sites as well? Do the question titles regularly omit important search terms that are present only in tags?
In my observation, adding the tag in front of the title doesn't help for many other SE sites. I did have a look at the most popular search terms that were used to find questions on Skeptics.SE, and I didn't find a single one where the search term was in the tag.
I strongly doubt that adding the tag to the title helps the SEO for questions on SE sites except SO and Gaming. And adding a tag that isn't an important search term does cause some harm:
- Google cuts off the title after around 70 characters, a long tag in front significantly reduces the space dedicated to the actual question in search results
- The tag occupies the most valuable spot of the title, in many cases this valuable space would be better used by the actual question title
Is my perception accurate that this feature might be doing more harm than good on many sites? Should this feature maybe be enabled on a per-site basis, instead of globally?
Here's one example where the tag lead to the question being cuts off:
The tag is perfectly fine, but it is not a search term people would use to find the question. And the wasted space in the beginning leads to the title being cut off early.