Yes there are undoubtably people flying for airlines with educational qualifications that are weak, poor or non existent. However not many in recent years. Whilst nobody is telling anybody that they cannot pursue an ambition because of a poor qualification portfolio, some are choosing to ignore the reality of the numbers game.
Firstly if you are applying for a flying job, it will be a prerequsite that you hold flying licence qualifications, and that is taken as a given. If you don't hold them the application is pointless and is dealt with accordingly. Nobody cares what percentage you scored on your individual papers, because that information isn't certified. You do not get an "A grade" ATPL or a "B" grade CPL/IR. It is a licence that simply required each component part was passed at some point. Every considered application will have this licence and therefore that doesn't help with whittling down the numbers.
Educational qualifications are certified and graded. They also assist an employer in forming an opinion on the level of a candidates effort and past achievement. This is true in many occupations, and flying isn't any different. Whilst there is some merit in the suggestion that a company looking for experience, will place a higher regard on that experience than it will on aged educational qualifications, the point shouldn't be lost that "wannabee" candidates for a job are not likely to fall into that category.
For those who suggest that "qualifications may be helpful, but are not really necessary", I am afraid you are promoting a delusion. If a company states an educational requirement for 5 GCSE's and 2 A-levels, or their equivalent, then that will become the benchmark used by the secretary that weeds out the application file before it is ever passed on for the interview selectors. If that criteria cannot satisfy the numbers required then it may be relaxed until the numbers are met, but nowadays that would be very rare.
It is also worth remembering that the best opportunities are likely to attract the highest number of applications and that numbers game again becomes all important.
Nobody is denying that success can be achieved by people without good educational qualifications, nobody is denying that jobs can be gained by alternative methods, friends or contacts, nepotism, luck , or any other method. It is simply that the numbers do not stack up by those methods. In reality to stand the best chance of success, you should place great importance on your educational achievement, because those potential employers will.