Well they don't have him in the same spot because Ovechkin and Stamkos shot right, and Matthews shoots left. They do tee up Matthews on the other side a decent amount, but peppering the blocker side is probably more effective than peppering the glove side.
But also, Matthews through his career has scored goals on the PP at a better rate than Ovechkin and Stamkos, and the 2nd best rate in the history of the league (400+ min) behind only Draisaitl (thanks to McDavid). We don't think of him as the PP goal scorer that Ovechkin and Stamkos were for one big reason. We just don't get the same number of PPs as Ovechkin and Stamkos got, especially in their primes.