That is true.
The more tags that get added to a game the more potential players there are that will try the game.
But when they do not see the content that they wanted to see, because it has not yet been added, they throw a fit and start whining in the comments about it.
It it far better to add the tags for things that do not yet exist in the game, as they are added to the game.
Fewer complaints, and happier players makes for better advertising.
At the most the dev could comment in a spoiler, what the future planned tags are, but separate from the normal tag location, so that people will know that those tags (content) have not yet been added.