Cuba is not stopping anyone from leaving for a while, but yes this was a policy during the Castro era.
That's a step in the right direction, if true. Do you have a source for it? This older article [0] says:
President Raul Castro said the regime will still decide who can renew or obtain passports. The government will protect "human capital" in its decision-making, and travel can be denied for "national security reasons."
Those deemed necessary to the Cuba socialist revolution — professionals such as doctors, scientists and engineers — can be prevented from departing. The "national security" clause worries some opposition figures.
[0] https://www.usatoday.com/story/news/world/2012/11/11/cuba-ex...
That's an understatement.
> controls on who can obtain passports are sadly the norm in the entire world
These restrictions are far from "the norm in the entire world".
Source? To prevent goalpost-moving, the restrictions we're referring to are:
The government will protect "human capital" in its decision-making, and travel can be denied for "national security reasons." Those deemed necessary to the Cuba socialist revolution — professionals such as doctors, scientists and engineers — can be prevented from departing.