No one here from Apple.
We are all, primarily, Apple product users. Just like you.
Apple is never going to go back and allow older devices to upgrade to a higher iOS.
That time has long passed.
Older iPads are based on 32-bit hardware/software and iOS 11 and 12 have moved on the all 64-bit hardware/software which is now incompatible with all older iPads.
iOS 10 needs a lot more hardware processing power that older iPads simply lack.
iOS 9 for older iPads was already heavily pared down and many iPad 2 and 3 users were complaining, then, that both iOS 8 AND 9 made their older iPads slower.
iOS 10 will only make your iPad 3 run even slower with little to no solutions to speed up iOS 10 performance on older iPads.
You'd be posting in the Apple iPad support communities complainng how slow iOS 10 runs on your iPad 3 with no more real solutions left to improve overall iPad performance, instead.
Apple is never going to go backwards and allow older iDevices to update to even iOS 10.
iOS 11 is not possible, at all, for any older iDevices.
iOS 11 and newer and new, even more powerful iDevices are Apple's future.
If you need older versions of apps that have moved on to iOS 10 and later, tap on my link below and choose the method that best works with your current situation.
CAREFULLY read and follow ALL directions. Especially so for my computer/iTunes procedure.
All three of my procedures/solutions work!
Downloading Older iOS 9.3.5 Versions of A… - Apple Community
Apps may or may not have older iOS 9.3.5 versions still available from the iOS App Store.
There are three ways to try/attempt to get an older version of an app. Pick the method that works best for your situation/circumstances.
Also, I would STOP using that nearly 3-year old Safari web browser, as it is, probably, not safe and secure to use any longer, and seek out a third party web browser that is STILL currently being updated and STILL being supported on iOS 9.3.5.
Heed my advice on this issue in my above link.
Good Luck!