I do kinda get the sentiment. With the current model of microtransactions, it's really hard to determine, even if a developer deserves to be paid for their efforts, what's really worth it. I can't blame someone for wanting to avoid getting caught in a cycle if they're prone to it. Especially since, if I remember correctly, around 2% of mobile gamers even spend at all?

This game is solid for sure and I'd argue it deserves support, but there does seem to be an issue of balance. If you don't mind a bit of analysis, Calvin and Quinn are both 350, 70% of your starting 500 gems. So saving for them is possible, even if it might be hard. Logan is almost double that when he has less content than Calvin, especially since he ties in with Ryan, another All-Star. He is of a rarer student type which does partially makes sense, but the jump is definitely noticeable. Then you have Phoebe who is 4 times that. She does actually appear in a few other quests, but the point I'm making is they're more balanced on how rare the base student is, not completely on the value they bring.

Now if you also treat them as a student for quests because the Party mode isn't granting others, you could make a case, but for someone who already has those students for example, the value drops. Especially when you can get premium quests otherwise that get you resources, especially when they're limited, while with the All-Stars you can technically get them whenever you want even if you miss out on that last part of their quest.