The alternative would, of course, be not playing it which isn't a great deal fairer.
Or alternatively the rules for the National League Cup in England, which features most national league teams and some premier league / championship under 21 teams. The national league teams are required to play a number (6?) of their first team from the previous game, injuries permitting. (Or something like that).
The upshot can be a load of strange substitutions, like here:
Follow live text commentary, score updates and match stats from Hartlepool United vs Middlesbrough U21 in the National League Cup
www.bbc.co.uk
(Link to Hartlepool 0 - 10 Middlesbrough U21s, with Hartlepool making four substitutions in the first two minutes)
Stupid rules get stupid outcomes