As others have noted, it’s true in some sense. I lived in worked in Malmö for awhile that has a very similar system, but not exactly so I cannot speak to minor differences but from my understanding it works similarly to Denmark. Yes, you get on the “list” from a young age. But it resets after the first apartment that you rent after you leave your parents house. So you might find a nice place but after that you need to start looking for another nice longer term place. It’s also not really as much required as it used to be. You can rent a nice place without getting on “the list” as there are places these days that do not utilize or care about “the list”. However to rent the nice places not on “the list” it is generally a bit more expensive and you have to show a bit more renting history. In general I can summarize it as follows: something like x% of renters (I think in Malmö at least it’s like 70%) use “the queue” or “the list” or whatever you want to call it, the thing referenced in your post. About 30% do not, and rely on more typical means of judging your rentworthiness. So if your income is a little on the higher side you would have no problem finding a nice room to rent without the queue/list.

Anyone in Scandinavia if I have pointed out inaccuracies please correct me. I lived in Scandinavia for some time but cannot say I fully understand the system.

It's technically true (the best kind). The more affordable apartments are usually rented out by a 'boligforening' and it's relatively common to give a membership/waiting list spot as a birthday present to newborns when the family lives in or near Copenhagen. This helps getting an affordable apartment when people leave home later to study. But there are plenty of apartments that do not require 18 years of waiting, it's just that the rent is higher.

As for my own experience, I'm moving to Copenhagen in a month for a job and I managed to find an apartment after searching for about a month. I'm moving from Aarhus (the second largest city in Denmark) and my new apartment costs 2.5 times as much each month, for which I'll get a slightly bigger apartment but much further from the center of town. My guess at the reasons for the price increase is ~50% higher rent in Copenhagen, ~30% moving from a 'boligforening' to a non-'boligforening' and ~20% the extra square meters in the new apartment.

I think the quality of life in the Nordic countries is somewhat overrated these days. It was really dependent on having a low cost of living, but now many things have been sort of left up to the market. Which means that property is quite expensive, and so is everything else. Social systems are less extensive. But there are high taxes, punitive taxes and somewhat low salaries for professionals. So the culture is sort of adapted for all this, but that only really works for those who have been grandfathered in. So regardless of the specifics it definitely isn't something to jump into without thinking. Unless you are aware and that is the idea.

If you're planning on having kids, the Nordic countries are still a good bet. "Free" (tax financed), high quality higher education and "free", excellent medical care mean a lot!

Edit: I've lived in Denmark since '91, and I never thought it was low cost of living, but definitely value for money.