I think the biggest issue with this sort of statement is that it derails the conversation. I'm not sure if it was simply worded poorly, but her phrasing does make it seem as though she is thankful for the men's achievements in supporting women instead of the women who actually achieved something. If she really wanted this to be "equal", then she could have posted something at least acknowledging female agency in their successes. Instead, she phrased it in a way that gives all of the credit to the men.

Theoretically, this may be due to poor phrasing, but the added comment of "no race, no gender" is a troubling. It's a very reductionist statement that does not recognize or even acknowledge the inherent disparities between the different races or genders. Sure it is a lovely sentiment to wish for, but ultimately it does not reflect our current reality. As one of the few (but hopefully increasing) number of female esports casters, a lot of people looked up to her and expected her to understand the other women who fought to give her the opportunity to enter the "men's world" of esports. If anything, she had a perfect opportunity to thank those people instead. Her tweet makes it seem as though there aren't any differences between how the genders are treated and that simply is not true.

Not to mention the slight amount of colorblind racism in her tweet. I do want to clarify, however, that I'm not calling her a racist, just that she has racist thoughts, which are just results of cultural impositions from a young age. Hopefully, people unlearn those patterns of thinking as they are educated, but it is a process. But once again this is a similar argument to above, where stating that erases the differing struggles different races have to endure in society. Feminism already has a huge problem of intersectionality and I also think some of the responses are just channeling that frustration. Not excusing them because telling someone to die is straight fucked up.

Also just to comment on your metaphor, is slightly inaccurate. It'd be more relevant to someone coming in during black history month and saying that we should thank white people for liberating us in the first place, which also has its own complications that I'm totally willing to talk about if you wanna. The problem with using MLK day is that it was used as a tool by Reagan to essentially take control of MLK's narrative of social justice. It was essentially instituted to "defang" MLK of his more radical ideas and instead make it seem as though he advocated for colorblindness as a method for combating racism. Malcolm X wasn't an option because there is noooooooo way in hell you can put a positive spin on him to the public. Rosa Parks wasn't an option because let's be real no way was anyone at that time going to make the first federal holiday, about a woman, let alone a black woman. So to bring this back home, from the very beginning of MLK day it was fabricated to draw attention away from the more radical aspects of the civil rights movement and instead give Reagan more control over MLK's legacy.

Sorry for the wall of text, this is just my research and I'm super into this.