Airlines don't and never have needed to sponsor pilots through their training.
In the UK, BOAC/BEA later to become British airways had a sponsorship ab-initio programme through their own in house training school at Hamble. Later this proved uneconomic and the infrastructure was closed down, with similar progammes contracted out to commercial flying schools in Perth and Oxford.
There were also a limited number of sponsorship and part sponsorship programmes offered in conjunction with selected training schools by a few other airlines. These programmes were relatively small and measured, and tended to arise during periods of high demand and limited supply, although the timing often proved to be erroneous. Nevertheless it was a very small part of the airlines overall recuitment intake from year to year.
The First Officers job was a that of a relatively experienced professional rewarded in accordance with the normal laws of pricing based on supply and demand. For the salaries paid, airlines generally sought the best experienced and most suitable candidates they could source from the military leavers or career improvers from other commercial companies. Low houred pilots may be sourced from specific integrated routes, but this avenue of supply was often expensive and not particularly desirable given the additional investment required and the lack of cost saving.
Then the market changed. A few airlines realised that whatever premium they could collect from economy/ premium economy/ club or even First. One of the most profitable seats in the house was right up front right. Instead of paying a cost to operate, this seat was actually a revenue earner. Such is the demand from the "instant airline pilot" wannabe, that this seat could be sold as part of a training programme integrated with partner flying schools.
The "dream" has a value, and it can be sold. The insurance industry didn't seem to care as long as the risk proved negligable. The regulator wasn't bothered as long as the minimum qualification was satisfied, and there was experience in the left seat. That is what has happened and it is a growing industry. Partial sponsorship is a good marketing tool. Many of those who don't "win" will still be invited to sign up albeit at their own risk. The partial sponsorship is recovered later as part of a reduced salary employment contract. All good marketing.
The dream may have a value, but the realization is likely to be much more mundane. Those aspirational jobs, notwithstanding the overall economy, are likely to much harder to come by, when they are not jobs any more, but a part of the "pay to fly" training establishment. This is a market that will probably only be brought to heel, when the public perception is alerted and brought to the fore. To some extent that is already starting. It is then that the regulator will be forced to act. If the public perception isn't wrong the insurance industry will have already put a price penalty into the mix.
Some people have always been able to find a way into flying as a career and the cost of it has been just another obstacle to overcome. It takes time, perseverance, luck and setting realistic goals as well as seeking out the opportunities as they arise. This concept of the "200 hour airline pilot" has got out of hand. It is a market and like all markets I suspect it will correct itself.