I wouldn't say speech therapy doesn't work. It worked for me. Sure it wasn't a cure and it didn't help until I got speech therapy again as a 19-20 year old, but a couple of things the speech therapist showed me worked for me. Sure, we are deluding ourselves if we think there's a quick fix or maybe even if there's ever going to be a quick fix our there and ironically accepting this fact can probably help us more than not accepting it, but I try to err on the side of positivity.