Or at least in all unclaimed systems?
Obviously, in an unmodded game, this requires many alpha cores, which probably means some dedicated grinding of Remnants to get theoretically unlimited alpha core drops. (I remember an image some time back where someone colonized the entire Penelope's Star system and had numerous cores installed on every planet.) I have not even attempted this due to the grinding that is likely required.
One of the reasons why I do not use cores is because I do not want to deal with Hegemony, even if they can be bribed away while player still makes a profit after bribe. It occurred to me that if I eradicate Hegemony from the sector (or at least decivilize all of their military and heavy industry), then Hegemony cannot (or should not) carry out inspections. Any income lost from destroying Hegemony should be more than made up if I have far more colonies than a colony-spec character can govern. Since alphas are effectively max skill colony character, player with a very long-term goal can ignore the colony skills and max out combat power.
Pathers will be Pathers, being angry just for having nice things (like good industries and synchrotron).
I wonder if the whole sector gets colonized by alpha-abusing player, then what happens to pop-up pirate and pather bases if they have nowhere to spawn?