I think that some people will assume that older machines have more value than they have. They might have some value as a collector's item, but as a computer, my out of date Raspberry PI 3 exceeds it in every way.
With a speed of 350 MHZ, 64 megabytes of RAM and 6 gigs of storage, the iMac G3 would be capable of only the most basic web browsing. Many, if not most, websites would not work. If it comes with some useful software, like word processing, then it would have some value.
Twenty years ago I remember trying to get some value out of an old 400 MHZ PC. It was useful for playing old games, but I seriously needed an upgrade, which I did. I went through about a five-year upgrade cycle, first getting a 2.4 GHz computer, which at the time seemed very impressive, and then a dual-core 2.4 GHz computer, and then a quad-core 2.8 GHz iMac. I still have the iMac, and I got a whopping 9 years of use out of it, but this year I have upgraded to a better iMac.
I have learned through experience that older computers have a high failure rate. Stuff just breaks, and the old machines aren't just worth fixing.