I can't say the same for Windows and Mac users.
Last two employers recommended FDE but made no strict requirements because apparently it was non-trivial for non-Linux users.
It's a no-brainer feature for any sufficiently fast portable device. If the installer supports it why would you disable it? I haven't had to worry about the data on my laptops should they be stolen for what must be over a decade now, GNU/Linux has supported it that long.
Me, I've been talking about PC users, generally. Not just Linux, and not just technical people. Sadly enough, I doubt that FDE is very common, let alone the norm.
And even worse, for many it'd likely be a curse. Inexperienced people don't do well at keeping track of complex passphrases, keys and so on. I've seen that over the years in forums where people plead for help to access TrueCrypt volumes. After losing passphrases, accidentally formatting, and so on.
I am only speaking to the prevalence of FDE among Linux users; it's not uncommon.
You're correct in that these are technical people. Most people running a GNU/Linux distro on bare-metal in their possession are at least somewhat technical, wouldn't you agree?