I think this is a very valid point! All we can do I go by what we see here. But until we have seen someone's work we can't say they are worse or better than anyone else. As you said, some are naturals at things and can become great extensionists without being hairdressers first. Thats not to say hairdressing will not add on to the service you give because of course it's all viable information and knowledge and the ideal would be someone who goes to do hairdressing because they are passionate about extensions and know the improvement it will give.
But in the end I'd want to go to someone that is passionate about extensions and knows the ins and outs of it and has done lots of research on it and courses. I don't need someone to be great at colouring as I find this is a specialised skill, but I need someone to give me great extensions that match and blend but there are various routes to get there. All am saying is id rather have mine done by someone specialising in extensions who does more than 10 heads a week than a hairdresser who gets the odd request for this. We just all need to see our own limitations and know what we need improvements with and what we can do to provide a better service. I think the problem lies a lot in people seeing it as a quick buck rather than a career and that is the problem. To get money quick even if the client doesn't come back.
Repeat business is what it's all about and in order to get that we need to give the best service possible and that is one that is thorough on health and safety, after care, placement, contraindications, quality and long lasting results that do not cause damage in the long run. But how you get there I guess is up to you, we can only just state our own opinions on here and weather people listen is another matter. I just think a lot of people are not clued up on little things like placement issues and contra indications and how not to cause damage and that is the people's messes we all end up sorting out. I think these hair extensions short courses are always going to be there but the problem is a lot of them not being thorough enough and not testing people enough before sending them out to do damage.