This is not a crazy sentiment.  JK Rowling has for a while now been doing this thing where she announces outisde of the narrative that certain characters are "diverse" in whatever way, but diagetically in universe within the narrative of the world itself there is little to no evidence to back up these claims.  Supposedly Dumbledore and Grindelwald had a passionate relationship-- but in a film very much about Dumbledore and Grindelwald this is explicitly only given as Dumbledore initially having had admiration for Grindelwald's philosophy - leading to their pact of not stopping one another - and how that got soured by Grindelwald's genocidal side.     Rowling has basically been cashing in on the diversity of her books/films without actually writing this diversity into them.  Anf this frustrates the fans because if Dumbledore and Grindelwald's relationship was as Rowling described in her Tweets etc. Then she is refusing to give the audience the real story by writing such a tame version of it in FB CoG