The truth often hurts
Well if the complaints were as vociferous as stated, then it suggests he hit a raw nerve. He's (almost) quite right - there is no shortage of domains, only a shortage caused by speculators hording them to create scarcity.
Where I think he is wrong though is in his statement that if you can't get "dot-x" you can go to "dot-y". It doesn't really work like that in a world where people expect you to be on a "dot-com". So if mynewbusinessname.com is taken, it's no good getting mynewbusinessname.anythingelse because customers won't find you. Instead, when a customer types in mynewbusinessname that you;ve spent lots of money promoting - they'll instinctively add .com - or their browser will automatically try it - and find themselves on a link-spam page (or worse).
In reality, you now need to find somethingnooneelsehasthoughtof.com and now register a multiple of additional tld variations for no reason other than to stop some spammer squatting on the other variations and trying to monetise your name. In other words, all these new tld constitute a shakedown where businesses have to register extra domain names merely to protect their name.