This narrative is really dubious. He was injured because the Oilers mismanaged him? So what's Kesler's excuse? Or Booth's? Did the Canucks "rush" the perpetually injured Salo? Or Willie Mitchell?
I know it's fun to think Lowe is responsible for everything bad that happens to the Oilers, but sometimes players just get hurt.
Well I agree in that Ryan Nugent Hopkins might simply never bulk up enough to withstand the rigours of NHL hockey.
That being said while he was obviously skilled enough to make the jump to the NHL level at 18, that was never the part of his development that was in question.. it will always be a "what if" but if he'd have been able to mature a bit more before playing against men he might have stood up to it better.
Maybe it would just mean that the chronic shoulder problems would have started at 20 instead of 18, but the fact is that when a first overall pick sees their career sidetracked for any reason people are going to wonder what could have been done to avoid it.
As to your examples the Canucks didn't put any of those players into NHL action when they were clearly too small so it's a highly imperfect analogy but yes they have clearly attempted to keep Ryan Kesler in the lineup (and get Willie Mitchell into the lineup) when they were not ready to play. The extent to which that compromised their health and ability down the line is definitely on the Canucks franchise.