Earlier quoted context omitted.
That's true in the same way that double taxation is a concern when setting up a corporation. It kind of is, but it's really not. Due to downvotes, I guess I better explain what I mean: Basically, EC2 provides instances where "if you restart your server you lose your data". You don't use those when that would be a problem for you, you use EBS backed instances which do not have this problem. Or you do it some other way…
I don't get the analogy. With EC2 you either lose your data when rebooting, or you have to use network storage (iSCSI) which has advantages and disadvantages. BTW, when I invest in a corporation, I do get double taxed. The profits are taxed at the highest possible income tax rate, then I pay 15% tax on the distribution of profits. Of course if I work for that corporation, I opt to take the "profits" as a bonus. I pay…
For data that must be stored, I can use a EBS, or a database instance.
Like the grand-parent said, you pick what makes sense. Saying that ephemeral storage is a bad thing would be true if that were all they offered, but it isn't, and it ephemeral images are sometimes preferred.