One of the important reasons why many blogs use Feed hosting services like Feedburner is that it can conveniently count and display the number of subscribers. However, whether or not to publicly display the number of subscribers on a blog is another issue. If the number of subscribers is less than 100, it might be better not to make it public, otherwise it could have a negative impact on increasing the number of subscribers.
If a page from a seemingly ordinary blog shows a very high number of subscribers, it is equivalent to implying that the content of this blog must be very good, otherwise how would so many people subscribe to it? On the contrary, if a very beautifully designed blog shows a very low number of subscribers, it means that its content is probably very average, or that the blog has been open for a very short time.