It cannot possibly be a 'shortage of quality pilots' when there is:
a) an abundance of qualified pilots looking for work, the vast majority experienced in regional, turboprop, air taxi aircraft;
b) the airlines have unanimously sidelined these pilots in preference for 200 hour guys, new to the industry, and looking to jump the experience hurdle by self sponsor themselves.
Now, you can make the argument that the pilots in situation 'a' above are inherently unsuitable because they are too moulded in lighter aircraft, etc... or whatever the current mindset of the airlines/flight schools is. You can also argue that pilots in situation 'b' are 'easier to mould', etc... Both view being championed by parties with a great deal to gain from selling SSTRs, strangely enough. If the situation was true, and supported by a relevant safety analysis with empirical evidence, then I imagine the US would have changed it's route to the majors a long time ago.
Frankly I believe the bottom line is that all airlines need to create revenue from tratining to compete with the mass subsidization of certain airlines by people paying ratings. I don't believe that pilots in situation 'a' are less suitable at all. They may be less willing to pay ratings, but they've worked their way up and earnt the hard hours. I've never seen any evidence of a high washout rate for experienced pilots transitions to jets or off regional jets onto narrow bodies. I think its easier for the airlines to dress it up in a more palatable 'safety' shroud rather than saying, 'we don't want the best, we want the cheapest'.
In conclusion, there cannot be a shortage of 'quality pilots' when a large portion of commercial pilots are not eligible to apply (1-2000 hours, no TR and not eligible to join a sponsored ab initio course) and therefore not assessed.
That's how I see the industry at the moment - and sadly I don't see it changing.