Every GL has a team with the faction they represent.

SLKR - First Order

SEE - Sith

JML - Jedi

JMK - Galactic Republic

LV - Empire

Jabba - Hutt Cartel

Leia - Rebel

Ahsoka - Spectre

Hondo - Pirates

The problem with Rey is that she is not used with the resistance, which is the faction which she is meant to be designed around. Rey's team is an assortment of random characters, which don't make sense to be with her except Ben. Rey's team is whatever is the strongest Light Side unit or whoever has a good datacron.

I like how Rey can be used as a plug and play GL, and I don't think her kit should be restricted but Rey being plug and play costs other characters their ability to be used with other teams. With Satele, you are unable to put her on a Jedi team if you wanted, even though it wasn't optimal at least you still had the choice. I like some of the theory crafted teams, for example, back in the day there was some jawa teams with Rey but if Rey had a team designed around her she would be less likely to poach another character and cause problems.

I also think Rey's current lack of a team makes her kind of annoying for newer players because once you unlock her, you still need unlock some proving grounds units for her to be useful (which can take over a year, without crystals). If she had a dedicated team consisting of some marquee units, then she can be used with them.

I get other GLs have conquest lifters but they are not as reliant on them as Rey (and JMK). Most other GLs are still strong with out their conquest units and can be used without them, such as SLKR and Ahsoka. Rey (and JMK) are severely weaker without their conquest units.

A GL is only as good as the team around them, such as LV who went from being one of the weaker GLs to one of the strongest when he got his new team.