They don't think that, it's done to simply raise awareness.If we really want to get racism out of this society we have to do things that matters. If Premier League think they can stop it by only taking a knee they are wrong. Give money to society. To schools. To social workers. To other education places. To people who really can affect and take care of this problem on micro level.
Racism a massive issue and it's not going to be stopped quickly no matter what you do or how much money and resources you throw at it. It's going to take time and if a small thing such as athletes taking a knee for 5sec impacts even a small minority of kids to be more opposed to racism like their idols are then it should be worth doing it for that reason alone, and as we've seen in this thread there's people who have had positive experiences because of it and as long as that keeps happening, and as long as we have people thinking like the OP, they should continue doing it.