There's a catch-22 when dealing with Facebook. On one hand, the social network works as an excellent free marketing tool that has a wide audience and acts as a venue for massive exposure. On the other hand, many of the idiosyncrasies of the platform make it extremely difficult to operate, particularly if you have a lot of content to post and not a lot of time to post it.
One of the biggest challenges is with scheduling images. Facebook "batches" images posted from the same tool into albums when more than one is posted in the same 24-hour period. Those using tools such as Hootsuite or Buffer are unable to post more than one image a day because the albums created on the Facebook news feed does not have a like, comment, or share button on it. One would have to click through to the individual image to be able to interact with it and few are ever willing to do so.
This oddity even holds true for Facebook's own post-scheduling tool.
The way to get around this when you have more than one image to post per day is to use multiple tools. Diversity in posting tools allows you to post one image a day from Hootsuite, then another from Buffer, then another from Facebook.com itself. Images posted directly to Facebook through mobile or the website do not have this challenge if they aren't scheduled, so this adds another picture posting opportunity; by posting some images immediately through the native tools, you can technically post as many as you want without the challenges that face scheduling tools.
Images are the key to building a strong Facebook page. The site is inherently visual and images perform much better than links or videos and perform a little better than basic text posts. When your goal is to grow your Facebook page's engagement, images are invaluable.