It can cut both ways... I'm remembering when Abbey was knee high and we switched from goldies to tropicals in her 10g. It was a well cycled tank but the youngster at Petsmart refused to sell us fish. Abbey cried like a baby. Now I probably knew more about fishkeeping than the child in Pet Care, but she had the rules and thought she was doing the store and us a favor. A funny part is that many years later (like 20), for a time, Abbey worked in Pet Care at that same store and I'm impressed with how much she learned.
The fact is that there is a lot of misinformation in many stores and on the interweb. There are so many
Hobby Myths parroted by well meaning hobbyists and wannabe gurus that really think they're helping someone newer to the hobby than they are. They merely echo what they have 'heard' from others they presumed had experience.
Cycling remains a mystery to many, especially newbies. But it's really as simple as having enough nitrosomonas and nitrospira bacteria to handle the ammonia and subsequent nitrites generated by the bio-load. And one doesn't need to wait 6-8 weeks for this. My friend
@Byron doesn't 'cycle' a tank. He's added a fish or two to a 'new' tank
WITH PLANTS and lets nature take it's course. Of course with only a fish or two in a 'new' tank, ammonia levels are slow to rise and the plants will use that ammonia as their nitrogen source as the bacteria slowly develops and matures.
I have setup many 'new' tanks by simply 'cleaning' a filter sponge from an established tank in the new tank water. Enough bacteria is transferred to easily handle a few fish.
And then there's the '
bacteria in a bottle' products. Now many still would have you believe these are just 'snake oil' and just don't work. I think this is largely due to when they first came on the scene, they were in fact the wrong bacteria. But since then, largely due to the research of Dr. Tim Hovanec, these products came of age and really can 'instant cycle' a tank (see the interview with Dr. Tim in the article linked above). Now there still may be some issues with transportation and storage but by in large, these products work.
I think perhaps the biggest problem is that newer hobbyists don't quarantine new fish and adding a sick fish to an aquarium can spell disaster. Now some suppliers quarantine fish and some even treat with meds, but many do not and regardless of wild caught or tank raised, adding new fish to an established tank can be like rolling dice. Maybe fine many times, not so much at others.
So there, I guess I've rambled on enough for now. I don't disagree that some stores are just looking at (needing) sales and/or employee's just don't know as much as they should. But like so many things, it's "buyer beware" and often in this case, many buyers just don't understand enough.