I was that person 54 weeks ago except I had no one to tell me I was wrong. I started with a black moor goldfish in a 2.5g tank. Poor little Wilbur passed way in a week from ich.
<not proud of this> I then commenced to buy 3 more feeder goldfish. A week later and they all died or jumped.
After that I decided that tank really was too small but in memory of Wilbur I kept trying.
Ended up getting a 45g tank, used the inch per gallon rule(with small fish not oscars) and it ran well for a few weeks.
It took me close to 4 months before I permed what cycled was.
I lost a lot of fish because of MY failure to do research beforehand.
In defense though, look at how fish are portrayed, many commercials and pictures display them in bowls with no filters or anything. It brainwashes people(like myself long ago), that fish are easy to care for and you can just plop one in and done!
Hopefully this person wakes up and realizes she's doing it wrong.