This is a simple reflection of the fact that Nix has a steep learning curve. People who persist generally have deep-enough interest or a compelling-enough use case to power through.
I feel like it's more of an indictment than praise; it implies Nix is relatively inaccessible to interested but time-constrained dabblers, which puts a hard cap on Nix's ability to outgrow its niche.
I'm the inbetween. I stuck with it for a couple of months, but ended up dropping it. It's just too slow and incurs a massive complexity penalty that I'm not happy about. I'd rather just deal with tarball rootfses and union mounts if I want an immutable system (and overwhelmingly I do not.) The reproducible builds are nice and all, but I'm not in a position to really take advantage of it. I'm sure Nix is killer for a modern sysadmin.
I'd much prefer just Plan 9. WORM filesystem and first-class namespaces.
If you don't mind a very limited set of software, the way tinycorelinux is setup can also allow multiple different tcz installed
These two Linux distros essentially allow two different versions of same software/libraries (glibc/python whatever) installed
(Gobolinux explicitly states that whereas I find it to be an unintended but elegant consequence for tinycorelinux but I recommend taking a look at Gobolinux)
I feel like it's more of an indictment than praise; it implies Nix is relatively inaccessible to interested but time-constrained dabblers, which puts a hard cap on Nix's ability to outgrow its niche.