i can see both sides of the issue. BOTH parties need to take responsibility. People should research what they are buying first - the biggest problem is that many people new to the hobby rely on fish store employees as their source of information. and why not? the person i buy a car from is supposed to be an expert about the car, and able to answer any question i may have about it. the person i buy a dishwasher or fridge from is supposed to know the specifications and good/bad points of the appliance. now, if i go to buy a computer and the salesperson doesn't know anything about it, then i will go and do my own research. however, a HUGE problem with doing this at a fish store is that the employees are uninformed and make stuff up, or are misinformed and pass on bad info (that in most cases they don't even know is wrong). they often won't just say, "i don't know", they will just tell the customer whatever they want to hear.
fish stores and their employees should be accurately informed about the products and livestock they sell, and if they lie to a customer or mislead them, they should be held accountable for it. there is a reasonable expectation on the part of the customer that a sales employee is trained and knowledgeable about the products they specialize in selling. used cars dealers notwithstanding, there is also an expectation that they will be honest.
as far as the customer - buyer beware, of course. you should do your own research, but the problem is that many times new people don't know there IS anything to research. you get a dog, you get it some shots (the vet tells you which ones because they are the experts), you buy it some kibble, and you walk it a couple times a day. if the dog gets sick, or mean, or starts peeing on your dirty laundry, THEN you might start looking for help. only at that time, when forced beyond your boundaries of knowledge, do you find out how much more there is to know.
You buy a fish, stick it in a tank, buy an algae-eater to clean up, give it a pinch of flakes twice a day. it only grows to the size of the tank, and the filter keeps the water clean. It will only grow as big as the space it has, and they only live a couple years anyway.
Until someone tells you any different, this is what it is to keep fish.
This is how I started. my family had fish before when i was little, and they didn't do anything special. I had a 10g tank, a filter, a bubbler, gravel, plastic plants, and a handful of guppies. When the water level dropped an inch or so, I added a pitcher of water. Every couple months, I took all the fish out, put them in a bowl, emptied the tank, and rinsed everything (including the filthy disgusting gravel) in tap water until it was clean. Then i put it back together and put the fish back in. And you know what? I kept all those guppies for 8 months until they were wiped out by columnaris in less than 24 hours.
Who did I rely on for help? The fish store people. I never heard anything about cycling, water changes, stocking levels, nitrates. Just set up the tank, throw these zebra danios in there for a couple weeks, and then bring them back and we'll sell you your "real" fish. These are also the people that sold me a goldfish for my 6g tank - because i wanted to grow plants in it, so i needed a messy fish that would poop a lot and fertilize the tank for me. Until I realized that things were going wrong, I had no reason not to trust the people who had "helped" me or to seek out more information than what I was given.
If no one ever tells you there is more to math than algebra, and you're perfectly happy with just knowing about algebra, you're not going to go out of your way to see if something like calculus exists. only when confronted with a problem you can't solve based on the information you have, will you decide to search for a better way.