[naloth]

There are a few limiting factors.

First off, giving an advantage to someone that already has it doesn't really do anything. So if you afflict Luck to someone that already had it or was previous afflicted (even running out the timer from a prior use), it wouldn't help them again.

Second, when you're giving an advantage typically the usage of a transient ability is under the control of the giver. Luck used in that manner would require the giver to pay attention and then wisely use it.

Third, it's not an automatic success. It's possible to fail or have the duration run out. It's just better to pay full price for some advantages.

Forth, being the party enhancer kinda sucks even if everyone else likes it.