Oh, I'm wrong.
There's a "new one"!
Uh, ...no I'm not...
Many users of these devices simply do not know how to get their mobile devices to run optimally under iOS updates.
Many others try do these major and minor iOS upgrades/updates purely over the air using Wifi, which IMSO, is a very unreliable way to perform any iOS upgrades updates.
I strongly believe that many of the older iPad iOS issues have been caused from "over the air", WiFi upgrade/update transfers.
I have been doing iOS upgrades/updates using my computer with iTunes for nearly 10 years, now, and have not had any major operational issues with ANY of my iDevices.
Also, many don't bother to either ask someone more knowlegeable with iDevices either by someone they know, Apple or signing up into these forums to actually get a solution or to learn something to fix it!
All they do is sign up for these forums to post their one and only whine, rant or complaint about how their iDevices aren't working properly and that it is ”Apple's fault" and "Apple upgrades/updates have slowed down their iDevices" OR "Apple is practicing "forced obsolescence!".
Somebody like...YOU, for example!
Under the Terms of Use (ToU) that you agreed to, when you signed up for these forums, any type of rant, whine or complaint is NOT allowed and violates the terms of use of these TECHNICAL support communities.
BTW, my iPad 2 and 3 models are running "mucho peachy keen" running iOS 9.3.5.
If YOU are having issues with your iPad, then maybe YOU should look to my previous post where there is a link to advice and solutions that will help you and your iDevices, as well as those, you speak about or know about, that are having similar issues with their older iDevices.
Before you come into a technical support HELP forum, spewing your accusations toward others, maybe you should, instead, come here to seek out possible fixes and solutions to your iDevice troubles and woes, first!
Hmmm????