Here's a thought/experiment on this topic. I'm a healthy 41 year old, 5 foot 10 around 170 lbs
I've been considering whether to add creatine, for all the reasons expressed in this thread. I am, however, reluctant to add complication, expense, and potential other impacts when a straightforward and simple solution will do. So i ran an experiment.
I took a Dexa scan in December, before beginning a strength block. I was going to take creatine, but realized then I wouldn't be able to determine whether the creatine, or just the strength work, created any change. So I decided to run one strength block without creatine and see what happened.
From December to mid-April, I did roughly 3 strength workouts a week and (more or less) maintained around 25 miles per week of running or hiking. Workouts were simple: 1 day of squat/OH press and 1 day of deadlift/bent over row. Every strength day, I did pullups and pushups and some bodyweight mobility. I increased protein intake, but nothing crazy. No supplements. I've done this routine for years, but really scaled back last summer and fall due to some injuries and endurance-based priorities.
I did a Dexa scan yesterday to see what happened. I gained around 5.5 lbs of weight, 171 lbs to 176 lbs. I gained 7 lbs of lean body mass and lost around 3 lbs of fat mass, decreased fat % from just over 16.5% to just under 15.5%. So decent results, with not that much effort, and no supplements.
Of course, this raises the question: would things have been even better with creatine? Maybe, for kicks, i'll try it next year and see what happens.
But if I'd taken creatine, I surely would've attributed some or all of the results to the creatine.
To be clear, I'm not saying that anyone should or should not take creatine. Just an anecdote that might add to the conversation. And if you're on the fence, maybe run an experiment to get a baseline and see if the supplement, or something else, is making the difference. Doesn't hurt anything.