Regarding the specific case of the question having [tag:ask-different], this question was migrated from Super User, having [tag:ipad][tag:iPhone] and [tag:ask-different] at that time. I removed these tags as they have a different usage on Meta Stack Exchange.

Despite the above being a single case, I think it might be fair to look at inbound migrated questions. It might be very likely that the site-specific tags were added before the question was migrated.

Some questions include site-specific tags because the question mentions a site. A possible typical case is OP's mentions looking for site recommendation because a question has been closed on, i.e., Computer Science SE, but the is not asking something about Computer Science SE. In cases like this, the site-specific tag should be removed because adding tags based on concepts mentioned in the question content is bad tagging, as tags should be added based on what is being asked, more specifically, the tags that better connect with the experts having the specific skills required to provide a specific answer to the question.