I've exercised on/off since school days. Recess in grade school, the PE class from 6th-12th grades, then I discovered weight lifting in college, got heavily into swimming since I was a lifeguard, and hiking since my at-the-time boyfriend did a lot of that.
I think exercise definitely CAN create a type of calorie deficit, but I still say you cannot out-exercise bad eating habits. After all, I was a very chubby kid until I reached age 12, and I played outside all the time... riding my bike, climbing trees, etc. So obviously all that "physical activity" didn't prevent me from being chubby little me.
But during college, weight lifting, swimming, going out to the clubs & dancing every weekend for hours - and I ate like CRAP (like college students often do!) with all the Taco Bell & fast food & mac & cheese & Chef Boy-R-D ravioli... still, 115-120 lb and quite healthy, TYVM.
During my mid 20's/early 30's is when I really started gaining weight & yo-yo dieting. I could exercise (walking or gym/weight lifting) and lose 5 or so pounds, but it was dieting that took off the most weight. And even when I continued exercising, if I started binge-eating again (which I did, time & time again) then I gained weight.
For some people, exercise is key. They cannot lose weight without it. For others, exercise is not key, they can diet & lose weight & be peachy keen with that.
I personally think it's best to
USE DIET FOR WEIGHT LOSS and EXERCISE FOR FITNESS. Also - quite personally! - I do a weight lifting routine about 2x a week that is only 20 minutes. That's because I incorporate two exercises in one, such as doing squats while simultaneously doing arm curls, so it takes me less time to complete but I still get upper & lower body benefits.
During this crazy*** hot summer (& living in the extreme south) I enjoy a good swim, usually 30-45 minutes, sometimes an hour, depends on my mood (& whether or not there's a storm going on, LOL). I do not walk. It's just too damn hot FOR ME. When the weather is more agreeable, I do walk. And bike. But 3x a week is about all I care for. I'm not trying to win any contests here, not trying to be "Miss Exercise, USA"

Just trying to feel my best, look my best, be "MY" best. Not anyone else's best.
Health benefits? You betcha! - my joints are moving better, I'm able to go up/down the stairs multiple times without breathing hard, and I can lift many things that some women claim they need a man for!
We're all here for support... advice... ideas... suggestions... shoulders.
And some people need to get off their soap box thinking
"their way is the only way to do it right." And that's all I have to say about that.