We need to make that clarification because if new gambling platforms do not come up and grow truly, there won't be any difference in the way and manners most of the old gambling platforms will behave, but with the constant introduction of new casinos that will brace up the old sites to meet up. with current demands. And just as you mentioned the existence of only a few old gambling platforms will only lead to a monopolistic market.
I think the user was trying to passage a message not to try a new casino but the reason wasn't concrete enough to back the statement. If we don't try New casinos, there is no way we will know things that we are missing as most of these new platforms come with great features and since their primary objective is to converge the user base from older to their own, they will have lots of goodies to attract new people, especially the bonus but while doing this, we shouldn't let down the basics things to watch out for incase of any red flag.