This is as much nonsense as the people saying to check with your doctor before doing literally anything in life.
People with bad posture and weak bodies just need one thing: start exercising today. Start with weak weights / body weight. Ignore the hand wringing online unless you're 70+.
I certainly have no personal investment in some folks who are complete novices at exercise to spin their wheels for another few years or decades. The point is, hiring a trainer for 5-10 sessions to teach people how to address their specific deficits and to teach them how to train will pay immense dividends.
People with bad posture and weak bodies just need one thing: start exercising today. Start with weak weights / body weight. Ignore the hand wringing online unless you're 70+.