A stroke damages part of the brain, and the movement problems that follow — weakness down one side, a heavy arm, a foot that catches when you walk, poor balance — are the downstream result of that damage. Physiotherapy does not repair the injured tissue. What it does is drive the reorganisation of the brain around it, a process called neuroplasticity, by getting you to practise the movements you want back, in a graded and progressive way, often enough for the nervous system to adapt.
That is why the single biggest lever in stroke rehabilitation is not which technique your physiotherapist prefers. It is how much specific, progressive practice you actually do. Everything else is in service of that.