Opposite experiences and bubbles i suppose haha, I remember the toxicity against casuals clear as day. Of course hardcore players have always been somewhat elitist, but the game-design during Heavensward favored this kind of behavior, which is not so much the case today. I was mostly midcore/casual during HW (Only cleared up to A2, then carried on A6, then A11), and playing on EU, so maybe different expositions to people.
I mentionned these contents first because I was answering to the idea of "casuals went on just fine", but also because they were thought of along the job philosophy of HW. Back in ARR, the community was priding itself on beating complex challenges like T9, and the game direction moved to an overall complexification of the game because the vocal playerbase was asking for that kind of stuff, which left casuals in the dust in most endgame content. Even back in ARR, casuals at least tried out the first two fights of a raid tier just for fun, but the focus on complexity, be it on job or encounter design, made Gordias and Midas a pain to play for casual audiences, hence Creator catering back to them more, making raiding more accessible (also, Gordias was also kinda shit altogether).
And then Diadem, which was supposed to be a more casual experience and the focus of the expansion, also shit the bed. For a good while, the only decent content you could really do casually in XIV were EXs and dungeons.
All in all I wanted to say that I agree with your overall point, but wanted to clarify that HW really was a rough time for the first 3 patches, and while I think casual content needs more opportunities for failure to keep being engaging and job design needs to be more interactive, I also think we shouldn't look back to HW for that.