A vacuum works to remove refrigerant and moisture by causing them to boil and flash into a vapor. Oil is suspended in the refrigerant under normal circumstances, so it is removed with the refrigerant.
A vacuum would not remove any liquid that is more than a few inches from the vacuum source. Material that did not flash to a vapor and was in a remote location like the evaporator or condenser would not be removed.
PAG, POE and mineral oil all have boiling points way above 200 * Centigrade, which means they don't flash to a vapor and boil off, even when subjected to a vacuum at temperatures less that 100* centigrade. FYI, 100* Centigrade is 212* Fahrenheit.
In other words, is impossible to get the system hot enough and vacuum low enough to make all the oil flash into a vapor and be sucked out of an A/C system. The technician who started the process would cook himself and all the equipment from the 100*+ Centigrade heat.