Yeah, the issue is that iPads go from “a device you can use for all your needs” to “a device which you have to pick specific tasks for”. Eventually, it gets to the point where so many of the bullet points of your usage pattern are gone that it’s practically pure constraints and impediments.
Some websites work (and that number will drop precipitously once the iOS version is old enough). Some apps work. Some games work. So you adjust your usage pattern to that which works. When it gets difficult enough, you have to get a new device and keep the older iPad for that specific pattern if you like. And the end result is the same. Sure, I’d never throw an iPad into a landfill, but I’d do that even if it didn’t work at all.
The only thing you can do is to find a usage pattern that works. Some people use them as photo albums, but it’s no longer an iPad, it’s a photo frame. Some people use them as music devices, but it’s no longer an iPad, it’s an mp3 player.
I never update iOS. I’ve been using original iOS versions since 2011. If I want to use an iPad like I want to use it, circumventing these issues once they get tough enough gets really old, really fast. Especially if you have other devices, which you HAVE to buy. You need access to your primary, full usage pattern at all times, anyway. If I cannot have 95% of my usage pattern, I might as well stop using the iPad completely.
The only aspect I can think of is a game. Say, so as not to drain battery life on a newer iPad I can use an older one, so that if I drain battery life on an older iPad it doesn’t matter as much.
But there’s only so much you can do, and like I said, if you lose enough of your usage pattern, then you might as well just use your primary iPad. Safari’s access pretty much collapses eventually. You can read with older iPads too, with apps like iBooks, that’s something else that won’t collapse.
