I think the selection is based on his favorite and I am not that surprised. There are other good casinos in the space he can also mention as alternative but I think he is already used to the ones he has listed.
You are right, what happens is that Sometimes we take into consideration the age of some casinos and the way they have become known and for me the most important thing is the degree of trust and reputation that we know that they are casinos that are honest and that have no possibility of being scammers, at least the possibilities of them becoming scam are very minimal , but Currently we as players have many things in our tastes, and Basically according to that is what we say which casinos we may like the most, that is clear, that is why I think that there are fans of many casinos, of course roughly there will always be a tendency of some more than others.
The age of the casinos can't be overemphasized my friend, this is even the first criterion that should be sought for as the more the age, the more the possibility to trust them. But other factors are still needed as age may not be the sole factor for reputation and integrity since there are many casinos that are older than many others but can't be compared to them. Nevertheless, older age exposes bad casinos faster because if casinos are still relatively new, you might be unable to find more information about them, but the casinos that have operated for more than decades, there is no way the internet will not furnish you with enough reviews about them.
Other things to look for are liquidity, terms and conditions, security concerns of the past and present, proficiency of their customer support service, payment mode, payment pace, the general quality of the platform, various limits, and options to play from. The list is just endless. Above all, the safety of our money matters most, if any casino has all the good service but errs in the safety of our money (whether intruders strike or it steals our money for itself), then it is not worth it.
I agree with you, the age or the longevity of the casino can speak a lot for it. Casinos like Crypto-Games, and few others have been in the industry for a vet long time and they have gotten good reputation because people have been using their services for decades as old as bitcoin.
And another thing I will also advise you to check when you want to know a good casino to have fun. You have to check the trust rate in casino reviews websites to see if the rating is good to play with the casino. You can use TrustPilot Reviews website and also check the Google to see other reviews centers to see the rating before you participate.