So again, it boils down to subjectivity. This is the crux of the issue. You feel they are not putting effort in and should not be rewarded. Someone might think you coming in with improper gear is not putting effort in. In both cases, there are no objective thresholds that determine a standard.
Now, if this were ranked CC, or if they ever implemented ranked FL, then I would absolutely agree with you that the performance is extremely poor and they should stick to casual mode until they get better experienced. However, since this is FL, there is nothing you can really do about it. I would be all for what has been mentioned before about having MMR that would pit people of equal skill together, but just like a duty in PvE, you get what you get in a queued environment.
This is the thing. People are carried in PvE casual content all the time doing exactly what you said. You have DPS not doing AoE on trash packs, healers either spamming cure 1 or doing no damage, and tanks not doing mitigation all the time. The content is still cleared.
I highlighted the bold part because this is 100% on SE. They have made so many people afraid to say anything with their ToS, and you can be reported for the smallest slight, so people just don't say anything. There have been many examples of people trying to hold others accountable and getting account actions. Absent of that, I think you would have more people calling people out for their play, both in PvE and PvP. I can't tell you how many times in PvP you have the group focusing on the team not in 1st and just want to call people out, but can't.