They are geared toward people who need to dive to get their science done. But here's a big secret: most anyone can take them through extension; all the scientists need qualified buddies, so you get not just a course but entry to a community of highly qualified divers who are doing interesting stuff and who NEED YOUR HELP! Your efforts and expenses, on their behalf, are also tax deductible.
About 40% of the people I train (and used to train) are non-scientists who want to participate as buddy divers. I welcomed them since because two scientists trading off buddying is rather inefficient, and we do not permit same ocean buddies doing separate simultaneous projects.