The CPL route isn't for everyone, and nor is the ATPL route. Each individual has to weigh up the balances of whats best for them, and what suits one person may not suit another.
CPL theory is slightly cheaper, and the academic workload / time frame is less with 9 exams instead of 13.
ATPL theory is more expensive, but gives you more options (however remote they may be). In the worst case your ATPL credits lapse and in 3 years you are in a similar position to that of someone who had done CPL exams.
Many things change in 3 years, both personal circumstance and the industry. You're gambling additional study, time and money for a time-limited shot at the North Sea. However that additional money / study may well not be an option for people financially, those who struggle with the theory or those who are juggling other commitments. Or indeed for those confident of their career path and/or the future of the oil industry.
If offshore employment prospects improve and you want to take advantage of them but only have CPL theory, you now have to do an additional 13 exams at a higher level to the 9 you have already done. If the route is CPL - IR - ATPL then the exam total is even higher.
Another consideration in the ATPL/CPL decision is which groundschool provider is going to suit your needs the best; the choice of provider is more limited at CPL level than an ATPL level.
There are people who did ATPL theory that has now lapsed. There are other people who progressed quicker than they anticipated, accumulated around 800 - 1000 hours instructing over 2 years and are being picked up for IR sponsorship.