Well, that's your experience but not mine. I haven't posted anything on social media, or 'told' anyone, or come out like that, and neither has anyone else I know in this situation. I do know one person who is trans and I don't think he ever'came out' and definitely would not have posted anything online due to his job. It just isn't done like that. But with celebrities maybe it's different. I suppose I am talking about my world and you are talking about yours and that's all we can talk about as it's what we know. I can understand why she did it like that because she is in the public eye, rather than say to one journalist, then another. I agree with you because I personally would not use social media, I don't get all of this stuff about posting what you eat! I don't 'hear' about any of this on a daily basis at all. No one is sick of hearing that people are straight, but here anyway, it is in every advert. every magazine, every newspaper, every news article. I know there are programmes about it like The Bachelor and Love Island but it doesn't appear a 'straight' issue there or people 'talking about it' because it is the default. Whereas if, for example, they did a 'trans' Love Island it would be viewed as a trans thing.
It sounds like your problem is with the media rather than with people, unless someone has come up to you in your daily life and said "I'm trans!" You are sick of hearing about it because it's in social media, the press, and online, rather than instances in your actual day-to-day life? I haven't encountered anything like this in day-to-day life. Well, we can only speak from our own experiences anyway.
I actually think we probably have very similar views on social media.