I’m one of them. I’ve been using Linux since 1995, and am switching over to BSD. It started with systemd taking over more and more of the system on Linux (I heard an interview with Lennart in which he said that they wanted systemd to “own everything between the kernel and the application layer.” ) and for me it has been buggy. Maybe that is just my systems, because were built long before the transition to systemd. My DHCP/backup server can no longer reboot without human intervention. It is the fact that I have a fixed address on the machine. I know I can do it “the systemd way,” but that seems as likely as not to change again. And their supplanting of the core unix ethos, like the absorption of su because Lennart thought it was a “broken concept” and so he set out to “fix” it. It’s the mission creep of systemd that gets to me.
At the same time, I started listening to BSD Now, and started reading about ZFS and OpenZFS, and it seemed rather compelling. Like BTRFS only it actually worked/was production ready. Well, I set up a FreeNAS box to replace my ageing Linux fileserver with the dying hard drive…Then I converted my desktop to PC-BSD. Currently, I am have a replacement firewall to replace my over powered iptables rig, and it runs pfSense. The next step is to replace my DHCP/backup server with FreeBSD, then probably my Proxmox-VE servers, which are holding on Debian/Wheezy because I don’t want to stick my hand into the sausage grinder that is systemd for my containers (openvz).
Another thing is that in general, the BSD community is on average 10 years older than the Linux community. The BSD community, whether on mailing lists or IRC, is friendlier and more helpful than the Linux community, in my experience. In the BSD community, I have gotten help with a FreeNAS problem or a pfSense problem in the PC-BSD irc channel. On the other hand, I was told " in the future, please don’t come here" because I asked a question about a broken upgrade in Debian unstable on #debian in freenode (which apparently is only for questions regarding Debian/stable. I also had to drop off of the debian-user mailing list because it devolved to nothing but bickering and flame wars, and had very little useful content.
I have no qualms about learning new things (hell, I am doing that with BSD and ZFS), but doing it to serve what I see as the hubris of the systemd team doesn’t fly with me. Just my 2 cents.