What is your league format? There is a set of selfie league rules within the IFPA book, and as mentioned above these act as qualifiers, but do not actually count towards the tournament games or value.

If you are playing against a score from yesterday, I agree with you, it isn't right. There is a lot of differences in strategy and mental focus when playing alone, let alone the environmental changes and game setup. And then there are plenty of cheating opportunities.

Preplay definitely contradicts the spirit of IFPA, which requires head-to-head play for a full value tournament or league.

I run a league that drops the worst week's score for each player. So if they attend 3 out of 4 weeks, they can still be competitive. It works really well and is a better alternative than allowing players to play independently.