I feel like Nintendo specifically NoJ is really trying to push Fire Emblem hard not just as a successful franchise in the west, but as one of their biggest brands next to Mario, Zelda, Pokemon, DK, and Animal Crossing. Fire Emblem will never reach the heights of those franchises and Nintendo trying to do this is like trying to move a boulder. 8 Fire Emblem reps in Smash is proof of this.
Push as much as you want, it's just not going to happen. Good luck coming close to Mario and Zelda, let alone Pokemon. AC is a very casual game (as I advertised it to my mother, "it's a game you cannot lose or play wrong") which is what makes it a huge hit with everyone to just chill with.
FE has a ridiculously large-yet-forgettable cast that fall into groups and usually cliches. Byleth is one of the most bland and boring primary silent protags (I'd honestly have been happier having virtually any other character from 3H as the Smash pick). On top of that, it's extremely complex for your average gamer, way too complex to ever become huge. Comparing Pokemon to FE because those are the closest comparisons in the series you've given, Pokemon's base game is stupidly easy, like nearly "mash A to win" easy nowadays. It has deeper systems that are a bit more complex, but virtually anyone of any skill level can pick it up and play. Casuals and kids? Easy babbymode gameplay with a ton of cute collectible critters to make your very own team. People who want to be competitive? You've got IVs, EVs, breeding, abilities including hidden ones, a plethora of moves and mons to pick from. People who want a challenging experience but don't want to play online? Well look for other Pokemon games, but some of them are a bit more difficult and offer a nice end-game (not Gen 8!). FE on the other hand, even on Normal Casual mode can still be a huge hassle. There's a ton of different stats, classes, and movement/terrrain to keep track of. Males and females have some exclusive classes from the opposite gender. You need to plan out your pathway early on or you will be at a major disadvantage later. If people die they won't get as much experience or skill, and yes, even on Casual Normal, you can-and-will flounder.
Bottom line is FE will *never* be as popular as the other games because it's not "easy to learn, easy to play, hard to master". When the floor is already very high up instead of the ceiling, it's very hard to get into for many people as they're put off from the difficulty and anti-casualness of the game. If they really wanted people to get into it, they'd make an even easier-than-Normal mode where Casual is also forced on instead of being given the option. The average person (even gamer) is not that great, and if there isn't room for casuals, there isn't room to be a massively successful series.
(also why even mention DK? DK is puny in comparison and doesn't even get 1st party development nowadays. Hell I'd say FE is larger than the DK series at this point)
Sorry but no... the fact that people still believe this is just... excuse my language but pathetic.
Max isn't talking about the last minute switch thing (which I thought at the time but don't any longer), he was saying that Sakurai wanted someone else for DLC 5 and Nintendo disagreed and pushed Byleth instead. That's also from Sakurai himself.