I'd say somewhere around mid-2008, when iPhone 3G / OS 2.0 came out, with the restrictive rules. Remember: the original iPhone didn't allow additional apps *at all* beyond what it shipped with. Everyone was expected to write webapps, which of course don't have restrictions on what they do.
And even then, it was somewhat possible to sort of justify it to yourself based on "it's just a phone, whatever, and you know, carriers are evil and stuff they had to, SRSLY!!". But now they've expanded the death grip onto a tablet device (and IMO likely will try to expand it further), I think it's a lot harder to make such a justification.