As other posters mentioned, using extra chunks might make it incompatible with hosting sites that remove them. Plus consider that they can be removed even perh

As other posters mentioned, using extra chunks might make it incompatible with hosting sites that remove them. Plus consider that they can be removed even perhaps unintentionally, if the upload process manipulates the image, it might convert the PNG file into a format-independent "Image" structure while in memory, which possibly discards this extra information. Steganography is a bit more resillient since it will survive basically everything but scaling or lossy compression, as the information is in the image itself (and thus a format-independent program doesn't need to take into account that data). Naturally, it is still liable to websites that assume images are photos and thus can be scaled and otherwise tampered with much less consequence.