As a relative newcomer to the shotgun world, I absolutely hate this advice (however well-intentioned it may be), and I'll tell you why: it's the single biggest way to turn/scare someone away from the shotgun sports. I will give you to examples.
Example 1: Me
When I decided I wanted a shotgun for shooting flying targets, I started
this thread. In the end, it was good because I got educated on a lot of things about the different games that I didn't understand, and I got some guidance on some entry-level guns. However, all the talk of fitting very nearly put me off the entire endeavor. I don't want to get "fitted", I want to shoot the goddamn events I was/am signed up for. I started to get nervous that if I didn't have just exactly the right gun, "fitted" by just exactly the right gunfit jedi, that my entire experience would be totally shit. WRONG. I bought what I now consider to be the Glock 19 of "sporting" shotguns, and I couldn't be happier.
Example 2: My wife
A bit after I bought my gun, my wife went along on a shooting event, tried my gun briefly, and then decided she wanted a gun of her own. "here we go" I thought, "this is going to cost me!" We went and took a couple's class together and they gave her (IIRC) an over-under 20 guage costing $2k or so. Eventually we wound up just getting her an a300 of her own and i figured having two of them wouldn't be bad if she hated it. She's fine with it. We encountered one of the local range hens that was running a ladies-only event one day, and the woman says "oh, you need a woman's gun, not this man's gun". Wife comes back to the cart and says "fuck that bitch, I like my man's gun" (have I mentioned how much I love my wife?!). We shot at a range out of state, and rented two guns, and they had a Syren. "oh, here we go again" I thought, "she's going to want one of these damn $2k+ shotguns when we get home". She shot the whole course with it, and at the end said "I don't see what all the fuss is about, didn't seem any different than my own gun".
So while I do think that this advice is generally well-intentioned, and I don't think that people are, generally, trying to offer this advice out of some sort of arrogance or snobbery (even though it can sometimes come off that way), I absolutely hate seeing it because I think the best advice is to get a gun and go shoot.