You brought up some good points here but I think I'd like to add that some but not all of the comics that fall under the genre or Romance /BL that have a lot of subs are kinda bad, but I think that since there is such a huge market for it there are will be plenty of people who just sub and follow the series simply because of its genre (from what someone said in another forum was that they had a series they uploaded twice one with the tag BL and the other without, the BL tagged one performed better and this happens all too often on Tapas and Webtoon, that a comic with nothing but cover art uploaded will get over 10k views and hundreds of subs simply because they used the romance tag or the BL tag)
It's really frustrating but it's understandable as I personally believe it's not that people wouldn't like to see what's outside their circle of interest but rather since they are so focused on their interest it creates a situation where unless your comic caters to their specific interest they'll never see it as they only care for that specific genre, but that's not to say there aren't rare instances where they might stumble upon your work but that is more based on luck more than anything and even though the market for romance and BL is huge it betters your chances of being seen by participating in that market
It's kinda like drawings and illustrations, those who don't draw fanart more often than not get ignored, as many potential fans only care about a specific character or series, and so this creates an opening for garbage fan artists, as a lot get very popular just because they drew an established character and then there are those who are extremely talented who also draw fan art just so that their talents won't be ignored
And to talk about the comics you brought up I think that they might be a bit misleading as the only one that's actually western is Bluechair which is a comedy comic and those have a pretty large audience already, while GOH, Lookism, Noblesse and Sweet home are Korean and the reason that's worth noting is that Koreans have a much wider taste than Western webcomic fans so those particular series have enough room to grow while being completely unique from one another without having to borrow from each other's specific genres or appealing to one specific market, and the only reason they seem to have become popular in the western market is because they are very well told unique stories but also because Webtoon helped push them and showed them to people who would otherwise not have looked for or seen these works because if their personal circle of interest. While on the other hand popular webcomics created in the west almost always follow the romance, drama, BL route (I love Too, Let's Play, Mage and demon Queen, Sub zero and Phantoms Paradise I included this one as many people believed it was a BL which is why many people were interested at first, the creator had to address the issue but to me it kinda felt as if the creator knew that the series would get attention for that's why they constantly tease BL in the series)
So yeah basically all I'm saying is that even if a comic is good like any work of art of its not tailored to meet the interests of the audience at large or if it's not heavily advertised to as many people as possible then more often than not the talents of those individuals will go to waste. And on the flipside there will be those who are not so talented who will take full blown advantage of the fact that popular genres have a large audience and in turn mediocre work will get popular because of this