There is NO denying the benefit of stretching and exercise.
If they provide the gains you are striving for and you have not hit a plateau with those gains, then stretch and exercise alone are sufficient to reach the functional goals you are looking for.
If you're like me (and many of my patients), you've maximized what stretch and exercise can do... THAT is when you could benefit from someone working on you to restore isolated mechanical mobility where it has been lost in order to return to function without chronic issues.
You're not stuck, you can get past your plateau and not fall into the 'I'm just getting old' belief!
Just because at-home stretch/exercise plateaus doesn't mean you "just have to live with it"!!!
Do you: 1) warm up certain areas for 15minutes to exercise to prevent straining an area? 2) stretch endlessly without much gain in flexibility? 3) notice one side is stronger than the other no matter what work out you do? 4) notice that your body is 'stuck' and can't move into certain directions no matter how hard you try? 5) tried endless combinations of stretch/exercise drills to deal with the same issue and chronic pain?... There is STILL a solution! Best physical therapy practice provides the external force you need to the joint to allow mobilization to the specific area so that: 1) you're not stiff in the same areas, 2) stretching works and you see gains, 3) you can start building strength in the muscles that used to remain inhibited, 4) can finally squat lower/lunge lower/open your hips/turn your body because you're no longer stuck, 5) no longer have to perform the tedious ritual to attempt to loosen your body to get it to work!