I appreciate the positive outlook you're trying to take. I can only speak for my own subjective experience, but I hope that it might help in some way.

Personally, I try to find a balance. If we've wiped a few times on a boss or trash mobs, I'll probably make some delicately worded suggestions, because I think "not failing" is a fair place to draw the line of when it's reasonable to ask a person to make a change. In addition, if we're wiping, the less-skilled player is probably also feeling frustrated, and finding ways to help the group succeed has the potential to alleviate that and promote a healthy group dynamic.

However, if the worst that someone is doing is performing sub-optimally, and it's not leading to outright failure, I try to take a step back, take a deep breath, and force my brain to focus on how they're just a person trying to have fun playing a game. I remind myself that I don't know their situation and don't know what kind of day they're having. I ask myself why my getting out of this dungeon a few minutes earlier is more important than letting this fellow Warrior of Light play at their own pace without feeling criticized. And when I do that, I usually smile, and suddenly instead of being frustrated that we're not going at the pace I was hoping to, I actually end up enjoying playing alongside this different kind of player and getting to be a supportive part of their journey. I can only speak for myself, but sometimes it also helps me discover that I've ended up getting too involved in being goal-oriented, and I'm focused too much on the destination to the detriment of my ability to enjoy the journey.

I hope this in some way helps!