I'm more-or-less fine with this sort of question.
First off, it's on topic in my opinion. A question might be off-topic if it were highly specific to the reception of anime in a particular culture (other than Japanese culture IMO). However, this question has a global perspective. It's about how anime is recieved, which is something that ought to be on topic here.
I also don't think it's opinion-based. A good answer to this question calls for some statistics, not opinions. If anything, it's less opinion-based than all the tropes questions that mostly never get objective answers or go beyond duplicating content that's already listed elsewhere on Wikipedia or TVTropes.
I don't think it's too broad either. There aren't very many possible answers, and answers themselves wouldn't need to be very long. Listing the 5-10 top countries by some statistic, and a couple paragraphs of explanation, would probably be sufficient. If someone already had such data available, it would not be a very challenging question to answer.
What this question may be is too hard. The data don't seem to have been collected, and doing it would require some sort of international polling that's pretty difficult. However, that is not a reason to close the question. If it were, virtually every nontrivial question on niche series would also be too hard. When a question is too hard, the proper course of action is just to not answer it. If you think it's too hard for anyone to answer, then downvoting (ideally with a comment) would be reasonable, but I'd be very surprised if no one in the world knew which countries anime is popular in. There are definitely ways one could study this, e.g. looking at export data, traffic to major anime sites, etc. It would not surprise me if there were academic papers which already perform this analysis. If it hasn't been performed, then it's pretty intensive to do well, which means that it probably won't get answered, but all that closing the question would do is change "hard" to "impossible".