And that's because the plastics on PBs are total shite - even the "newer" G3s. My mint condition Kanga that I've owned for years needs work (death chimes on startup) and believe me I've thought long and hard whether its worth destroying the plastics trying to resurrect it.
And don't get me started on the iBook G4s. My parents bought me one brand new in '04 - plastics on the top cover started disintegrating after three years of regular use. Logic board died shortly afterwards.
If you want longevity in a laptop, you can't beat a ThinkPad 600E. Only thing that goes wrong with those are the stupid rubber covers for the ports.
As the resident PowerBook guy here, I have a few thoughts on this perspective.
Out of all of my PowerBooks, I've had exactly three units that have completely intact hinge plastics (besides the newer G3s and G4s): My 100, 180c, and my 240MHz 3400c.
The rest have all cracked in some way. However, what I can say is that there are always ways of fixing it. The 100 series and 500 series PowerBooks have 3D print templates that you can print, install, and fix the hinges that way. I've installed them in my 145 and my 170 and they're both doing great now. My 150, not so much, but it's an especially bad case.
The original PowerBook 100 doesn't have hinge issues usually.
Colin from This Does Not Compute designed a standoff replacement for the color Duos, that could easily be modified to fit the Grayscale models too. He hasn't shared the STL files I think, but I'll bet he'd send them if you sent a PM on TinkerDifferent. I could do that if you aren't a member there, but if your screen is junk too then there's no point.
The 5300 series can be epoxied, as can the 3400, 2400, Kanga, etc. The 1400 is a special case because of the way it breaks, but epoxy will fix it (but will be ugly). Point is that there are ways to work around it, but I'd understand someone not wanting to deal with that sort of thing.
As for being worried about taking machines apart because of plastics - I've found that simply isn't much of an issue, if you're careful. For your Kanga, it's more than likely that the system has fallen victim to a leaking PRAM battery, so it's unfortunately probably toast, but it's still worth checking. I made a quick video tutorial on how to get it out here:
When taking apart the couple dozen vintage laptops I have, I'll lose a clip or a standoff here and there, but that can usually be mended with some epoxy or plastic weld. Again though, this sort of thing definitely isn't for everyone. I'd understand wanting to avoid the vintage laptops because of all this.