First, this question is hard to answer within the 20-year-rule. The situation now is quite different than it was 20 years ago, which is quite different than it was even 25 years ago. So the question is effectively "was the US a major barrier to peace 20 years ago".

Second, keep in mind that Noam Chomsky isn't a historian. He's not even an academic in the field of international relations--he's primarily a linguist, who gets a lot of press for his political views for reasons I don't quite understand.

Anyway, as of 20 years ago, the answer to that is pretty clearly no. 20 years ago, the Oslo Accords were being hashed out, which established the framework of a relationship between Israel and the Palestinian Authority. They had legal authority, were jointly patrolling territory, etc. And the Oslo Accord was substantially negotiated with the help of the US. 20 years ago, an end to the Israeli-Palestinian conflict was seriously under way.

But without the US, would the conflict have reached resolution earlier? The answer on that is probably not. A two-state solution wasn't terribly popular on either side. The PLO wanted Palestine to be the territory of both Israel and Jordan. While a two-state solution is pretty universally accepted in Israeli politics now, it wasn't in the past. While the beginning of the Oslo Accord was conducted without the US, the parties were initially brought together by the US and USSR.

In fact, there was an attempt at a peace agreement prior to the US's involvement, after the Israeli War of Independence. But without a world power like the US pressuring either side to make an agreement, nothing really came of it.

For within the last 20 years, you may want to check out /r/Ask_Politics.