wainy:
A Large empire has no special need for one free settler and one free worker. You need that when you're small, not when you're large. They're huge bonuses at the start of the game. At 1000 AD? Not so much.
Let's posit a mature empire with 10 cities, each with pop 20+ with the capital nearing 30. The new Aristocracy alone will net you in excess of +20 happiness, and Monarchy will grant more than +10 with a +10+ gpt bonus thrown in as well.
Just as well, Oligarchy will allow you to build up your military up to 10 units, without any maintenance costs whatsoever until you ungarrison them from your cities to go to war. That's potentially 100% of unit maintenance just gone in the entire military buildup phase. The additional city defense is just gravy.
Landed Elite, Monarchy, and the Opener are the only Policies that only affect the capital, but even then, the happiness gains from Monarchy can be used to fund happiness concerns in outlying cities, even though it's dependent on the size of the capital.
I'm not saying that anyone should forgo Liberty's altogether too-good benefits, but those benefits are much more beneficial for small startup empires, such as you have at the start of the game. Taking up Liberty later on, if you should choose to skip it entirely until Industrial, is distinctly underwhelming.