To make cup as fair as possible, cups may be:
(1) arranged with teams from same level, and randomly drawn;
(2) arranged with teams from same level, and drawn according to team average quality (may be for top 14 players only); or
(3) arranged with teams from same level, and drawn according to team average quality, available cash, tokens & even green packs, etc.
I think all 3 methods are fair, and I expect that real strength of teams for cup with method (3) will be really close. Even more factors may also be considered in drawing, e.g. average number of trophies obtained by the managers per season.
Cups can be fairer, but they are not necessarily more interesting.