Comment by aftbit

For me, the reason is that Synology is not open source, and additionally because their NASes are overpriced for their size and capabilities. I have a 12 disk NAS that cost me a total of $500 (before drives), with no software licensing fees at all, and that's not even an especially cheap one. My earlier NAS was slower but only $120. Of course, it needs a deep 19" rack to mount, but that's actually an advantage for me, as I have a dedicated homelab rack to play with.