My question/suggestion is pretty straightforward. The alternate-class-feature tag seems to be very narrow and rarely used, and it has no tag info so it's not clear how it's different from the existing and more commonly used class-feature tag.
No, the tags should remain separate.
In 3.5 and Pathfinder, at least, ACFs are their own thing, with their own rules that differ from the rules for normal class features. People collect lists of them, they have their own header in rules docs, they generally appear in a different chapter in source books from regular class features, etc.
In short, ACFs are their own topic, and it's useful to have a category about them. It's easy to imagine questions that are specifically about the rules for ACFs, like:
- Can you trade away the same class feature twice for two different ACFs?
- If you gain a class feature as an ACF, can you then trade it away again for a different ACF?
(I'm honestly surprised neither of these questions is already on the site.)
It's reasonable to have a tag in place for questions like this.