Travel like that was never "reserved" for explorers, missionaries or high ranking dignitaries. If you had the money/resources, you could go anywhere.
Now there is a "caste" system of countries that have Visa on Arrival, Free Entry, or Visa required where you have to prove that you are financially capable, or even wanted in the country, or promise not to work or be illegally employed/compensated.
And then that alongside many countries in the developing world that still have undocumented people, no birth certificate, no identification, no tax ID, etc.
How does a country verify someones birth? Especially if someone wasn't born in a hospital? In the west, until 1950's, mostly this was done via church records. Also, are you granted citizenship by birth or only through parents? (Big deal, especially for Puerto Rican births - or countries that don't recognize foreign births in their land, e.g. United Arab Emirates / Saudi Arabia - even Japan or China, where sure you can be born there, but that means absolutely nothing.)
So, no, it isn't really a greater system for international worldwide travel - it is a system of control to ensure someones identity is who they are and that the country they are form atleast certified to some standard that their name, their picture, their birth date, their location of birth are somewhat tangibly real.
And this isn't even getting into information sharing. The above is just a standard, that now is "machine" readable and has an RFID so that collection is more easier for the state.
Context is amazing, isn't it?