User blog comment:Fairingrey/March 20, 2015 Another Tiny Future Content Update + Wiki Stuff/@comment-172.9.190.84-20150321182627/@comment-24802125-20150321193801

Someone can explain this more in detail but in short: Make account, register account, save password somewhere, play until you have 1k/2k crowns or however much you want and acc is >lv 20, keep the account for later until the packs come, rinse and repeat until you have lots of these reroll accounts.

It's one strategy of getting really good units. What you do after is if you get anything good you just funnel them to your main account.