Anyone, "genius" or otherwise, who suggests forgetting your back up, doing a fresh install, and installing all apps one by one, is not solving the problem at all.
First of all, the springboard crashes will return if you install too many apps--as has been tested by several people in this thread.
Second, even a fresh install (and HOURS of manually choosing apps to re-install) DID help, it's still a MAJOR DATA LOSS BUG.
If you cannot use your backup, you lose all your data. THAT is the problem here. If Apple support tells you to throw away all your data, that's no answer.
I had around 1000 apps running perfectly on my iPhone 5. My 64 GB iPhone 6+ crashes every 3 seconds when using the home screen, every 30 seconds (literally) when asleep! So I HAD to throw out my entire backup, or I would have a brick. NOT because the backup is corrupt, or because some rogue app is able to kill the home screen (both of which would still be Apple bugs anyway). It's simply the number of apps.
So here's the data I lost:
- All my Camera Roll photos from over a year. (Thankfully I exported most of them to another place not long before selling my phone--but albums/organization are still gone.)
- All the creative work in my productivity apps: notes on projects for work, notes on characters and elements from games I'm building, tons of local hiking maps, a dream journal, PDF product manuals and reference docs I had gathered, and various pieces of artwork and music. Gone. NOTHING can get them back until Apple fixes this bug.
- All my hundreds of hours of progress in games: high scores, levels unlocked, story revealed, upgrades earned. I worked hard to unlock new stuff I cannot ever see now. ((Yes, SOME apps can cloud sync in a way that's separate from iCloud backups... and sometimes that cloud sync works. Sometimes not—and some people don't opt into it for every app. I certainly don't. Half the time you'd have to make some new account, with a new password, and give your email address to some random server.)
- (And for some people, they'd have spent a lot of IAP/currency to get that progress! All burned away: you can't "restore purchase" for consumable IAP.)
- What if I had noted some vital passwords or lock combinations on my phone? I'd have my phone backed up on my Mac, and backed up to iCloud, and feel secure. THAT is some serious data loss. (Luckily, I'm more careful than that.)
That kind of bug is SO big that even if it affects a minority, it should be a priority for Apple to fix (and tell their Geniuses about). Do we HAVE to have 1000 apps? No, but game collectors WANT to, many people do so, it used to work just fine... and Apple never warned us to delete all our apps before getting the new iPhone. At which point it's not a number-of-apps bug (that's the cause) it's a LOSS OF BACKUP bug. What if everyone with three Qs in their name lost their entire backup. Should Apple say, "well, that's only a fraction of the users who bought from us, so too bad." No. They should fix it.
Even if you wanted to keep just a FEW apps from your backup, you can't: you'd have to restore, then manually delete hundreds of apps... using a phone that boot-loops when you try to use the home screen. Impractical. I can't even flip past the third home screen without freezing my 64Gb 6+.
Android has long had problems if you install too many apps. I was grateful not to experience them... until now, and worse than Android: my Android friends would have a slow phone, not a brick. (Granted, they hit that limit with fewer than 100 apps--and had no backup to bring to their next phone no matter what they did. No backup means no backup to lose, I guess...)
Insult to injury: it has taken SO long to fix this that I now have important data on my stripped-down fresh install. I'll have to lose all THAT if and when I can go back to my main backup with all my "stuff." I'm trying hard never to use my iPhone for important things that I can't afford to lose. Great value for my money... I would have much more functionality if I had just kept my iPhone 5.