Still running the same distro here, from 1999 (and am mercifully free of systemd, pulseaudio, etc). All upgrades have been done by downloading and compiling from source, with the exception of a small number of large programs/drivers (specifically Firefox, Palemoon, OpenOffice, Java, nvidia driver). This 'in-house' distro gets copied onto all new computers, so there's about 50 or 60 running it (including a few laptops). So what doesn't work?
In short, not a lot. Occasionally have to 'chmod a+rw' something in /dev (easier than running udevd), but that's about it. Written a couple of init scripts, fixed a few others (all very simple, maybe a day in total).
The best bit is, if anything breaks we can fix it - easily.
As to why modern distro's are so complex: "follow the money". If everything was so simple that no-one needed support, well, there goes the business model of all the major distros. So it's not unexpected they put developers in change who like 'elegant' (read complex, bloated, impenetrable and obscure) solutions - it means that end-users pretty much have to fork out for a support contract (or spend a *lot of time* on inhouse admin).