If Carmack and others managed to do great without a formal degree good for them. But they're outstanding people and are more the exception than the rule. If you're as talented as these guys, fine let your skills speak for themselves. But assuming every person following this 3 month "program" will now call themselves a programmer is something completely different.
true enough. but whether CS knowledge is required is a more interesting question. John Carmack (picking a name from your 'homegrown' list) is extremely knowledgable about algorithms, computer architecture, graphics etc.
of course, it also depends on the definition of 'good engineer'. If you define it as "someone who can build a simple CRUD app in Ruby on Rails", then probably very little CS knowledge is required.