Not likely. These things work or they don't. They don't "run poorly" due to some hardware not being installed at factory: they don't run at all.
Much MORE likely is the human element. FAR more "faulty parts and build quality." OK went a lil far on THAT one..... lol!
Michael
Hardware tends to have a pattern to failure. You get a crash one day and nothing seems to be wrong. It works fine again and you forget about it.
Then it crashes again and while you are investigating the problem it crashes again. A few hours/days later it keeps crashing every time you attempt to use the device.
Hardware tends to fail in this way. A connection being broken due to oxidation, memory chips failing due to temperature overheat, disk sectors with poor magnetic coating finally breaking down.
Working in a big data center we see the problems all the time. And you wouldn't believe how often it finally goes south when you do one of the following: Reboot the system for the first time in months, install a new piece of software or even more frequently when you install/upgrade a new OS. Things work fine in the steady state, but as soon as you stress the system by doing something like updating an entire OS or firmware the system collapses.
I know the iPad is Solid state and hardware failures are rare, but they are not impossible. And they tend to appear with the same patterns as other hardware failures. Now if you take rare and multiply it by several million devices you get a number of failures that will surprise you.
I'll grant that other variables are just as likely, but dismissing the possiblility of failures in hardware during an upgrade just doesn't track with observed reality.