I would argue it would have sped up his development or raised his ceiling (more scoring than 25/50 at his [current] peak). By rushing to the NHL, he spent time learning and focusing on the playstyle that kept him in the lineup - 4th line style play with grinding, defense, fighting, and big hits. That time could have been spent at the OHL and then AHL level focusing on offense, PP (not until 18-19) and PK (not until 15-16). As I already outlined from his production numbers, it's not like he was dominating in juniors. He was the 5th highest point producer and 6th highest goal scorer on his team, and he would have benefitted by (probably) being London's leading goal and point producer in 13-14.
I'm very glad he surpassed being a pure 4th liner, but I cannot say that it was good for his development. This is a purely academic discussion since there is no way to know for sure. Is it better that Lapierre got significant AHL time in 22-23 (which thus made him a better player in 23-24), or would his natural talent have emerged regardless of where he played in 22-23?
(unrelated - the trip down memory lane of the 12-13 and particularly 13-14 is a very dark time). Glad we rebounded in 15-16.)