I have a friend who is a teacher, who used her Mac Plus until year 2004 as her MAIN machine.
Not kidding.
I had to explain to her the necessity of email...
So I "updated" her to a 266mhz iMac G3 tray load with more ram and bigger hard drive. To run her old OS8 or OS9 programs and files.
She's still on that machine and I have to explain to her how she needs Panther or Tiger because the old internet explorer for the Mac no longer works.
Well, some people have limited needs.
OS 9 is still useful for some things, but you're right that there is simply no acceptable modern browser for it, unfortunately.