Not wishing to get into a flame war but a few points on your statement...
- I do admit that getting Linux running on a PPC is not as simple as putting in a disk and hitting 'next next next' but it is actually quite close to that currently - really only getting 2D and 3D acceleration is the common remaining bugbear and I'm sure this depends which PPC Mac you are installing on.
- Re the 'plethora of apps' there are hundreds and hundreds of apps in Linux and whilst some may be not quite up to some OSX apps many are ahead. Eg. Gimp may not be up to PS standard fully but it has more than most people will ever use and its up to date and will keep being updated (in my case with Ubuntu Mate until April 2019).
- I run the latest version of VLC, full real version of Firefox, Thunderbird, Clementine for Music (which is an awesome music player/organiser) I use Scribus for DTP, Shotwell instead of iPhoto - Libreoffice v5 which runs very fast (2 seconds from clicking on it) - I have access to my Privateinternetaccess VPN through native network tools - I don't have to run an old and unsupported version of Tunnelblick - I use Liferea as an RSS feed news app etc etc/ All my apps are modern, up to date and continue to be updated.
- The OS is secure and security updates and holes are patched.
- Performance is excellent - a real eye opener for me - from a fresh boot Firefox with a fair few plugins starts in less than 3 seconds.
- After the (I admit!) pain of installation and configuration (mainly to do with the graphics which is now sorted) it has been rock solid stable, not one app crash - everything just works.
- A lot of people have put in MASSIVE efforts for FREE to get Linux running on PPC, I think posting that its s*** is both disrespectful and too much of a blanket statement - It's certainly not s*** for me and I appreciate very much what these Linux coders have done to make a machine that is this old and this obscure still be usable with modern software today.
Having said all that I don't expect it to run that well on a G4 iMac, because it is running 2017 software on a 2003(?) architecture and there is no way around that but on the G5 it is quick - not just quick for the machines age - quick.
I'm not bashing Leopard/OSX, if I could run a modern supported version of that today I would instead of Linux but as that's not an option I will continue to support the massive efforts put in to keep my machine going in a modern environment.
Linux may not be for everyone, you need some technical skills to get it working but once over that install hurdle it will remain stable, updated and secure with literally hundreds of excellent apps to use.