The FDA and patents certainly do restrict alternatives.
But the FDA requires testing to show that an alternative is functionally equivalent. All this talk about how there would be more alternatives, if not for the FDA, is silly, unless we know that the alternatives would do what they are supposed to do (without doing things that they really should not do).
Your criticism is silly. Requiring rigorous testing is a good thing. It increases the cost of entering the market, and so restricts alternatives, but it does so in order to ensure that consumers will get what they actually need.
(Patents, meanwhile, don't restrict actual alternatives, but restrict who can sell the particular drug in question for particular purposes.)
Hey, I have Libertarian leanings, but anyone complaining that the FDA is unnecessary goes rather too far in my book.