Never claimed that it was without problems. But look at the timeline: Steve Jobs letter was April 29, 2010. About a year later Adobe stopped development of Flash on mobile (that's when they really killed it, the next 10 years were necessary to implement the decision basically). You really think that letter shifted mindshare in 1 year? Trust me, the opposite was true, there were some really big players that wanted to announce flash support on mobile and were caught completely off guard.