I'm going to break down exactly why this is so infuriating for many people, because there's a lot more to unpack here than just "Another fucking FE character."
First of which is the fact that the franchise was on the brink of death not even a decade ago, yet it somehow has as many characters as Mario and more than Zelda when other, much larger series with a far more varied history in both the gaming world and in Smash (like DK and Kirby) have half as much or less.
It's the third dual-gendered generic avatar character in a row. It was a breath of fresh air at first after the string of main character lords (Ike notwithstanding) but now it's become its own issue of repetitiveness.
This is the third advertisement character for FE. First was Roy (who's game wasn't even out yet when Melee released and was a Japanese-only title), then Corrin (Fates was only out in Japan at the time of reveal) and now Byleth (who's game isn't even a year old yet). The only other franchise to have this kind of pattern is Pokemon, and it's an infinitely bigger franchise. To add further onto this, other characters got snubbed specifically because they were too soon, like Rex and Spring Man, yet FE gets a free pass for the second game in a row because it's just that inexplicably special.
From a design standpoint, Byleth isn't much different from his contemporaries in both form and function. The fifth blue haired twink of the franchise, and despite what people will try to say the moveset isn't all that unique. Like the rest of the DLC crew a lot of his moves are lifted from others (Link's bow, Simon's whip, Joker's grapple, ect.), the only truly distinct trait his has is the lance. On top of this, the "Swordsman who uses a more than a sword" bit they touted has already been done by FE characters before, twice.
And finally, there's the elephant in the room of how they duped people out of their money. It was 100% deliberate that Byleth was the last character of the pass, because they knew damn well fans were gonna be pissed after the hell raised over Corrin, so they sneakily put him at the end after all the hype characters, when most will have already bought the full pass and can't decide to just not buy Byleth because the money was already taken months ago.
