One thing I've noticed about photography compared to most other mediums of art is that photography is populated by a much larger proportion of crafts people than artists. To a craftsman/woman the quality of the image is determined by it's adherence to a set standard, or social norms. The goal is to create a product that aligns most accurately with the patron's expectations.
To an artist, the quality of the workmanship is judged by it's fidelity to the artist's vision. It's value is not determined by the patron's expectations, but rather by societies reaction. And sometimes that reaction may not be contemporary. Often times great art is not defined by it's ability to adhere to the rules, but by it's ability to exploit new exceptions.
Neither perspective is right or wrong. There's room in this world for both. I'm sure we could all imagine a bride being horrified to find out she hired a fine artist instead of a wedding photographer to document her big day and got back a bunch of blurry shots of trash bins. And I'm sure we can all imagine being less than impressed upon entering a museum and seeing a bunch of ordinary faces in Glamour Shot poses and lighting posted on the walls. And there's also some middle ground here between the two extremes that some may like to delve into. The craftsperson is in no way inferior to the artist, and the artist is in no way inferior to the craftsperson.
My point is, there's a reason why some say 50mm on a 135 camera is too short to be an effective portrait lens. And there's a reason to ignore their advice completely. You just need to know who's giving you the advice, and how that relates to what you're trying to do.
Also, as per the Dunning-Kruger effect, try not to put too much stock into anyone who claims to "know a lot" about subjects as complex as photography. That's just general life advice made doubly important in the age of the internet.