I'm not saying it can't be done (although McGinn had nearly 200 first team appearances under his belt before he moved south), just that it's very rare - and in the case of Motherwell youngsters, unheard of. Scott isn't consistent enough to get a regular start in our team right now and as Robinson pointed out, needs to learn how to use his size better (and score more goals). No doubt he has the potential, but that's as much as you can say.
It's changed days when guys like Joe Jordan, Steve Nicol, Alan Hansen, Steve Clarke, Andy Gray, Pat Nevin etc. would move from Morton, Ayr Utd, Partick Thistle, St Mirren, Dundee Utd or Clyde to make a quick impact at top English clubs.
Ian St John was probably the last one from Fir Park to do that!