Its just kinda stems from the bashing of Corrin by some of Ike's mains. The problem really starts at release with Corrin being a character that does many similar things Ike does well, but better. While Ike only has a couple things he has better than Corrin (from a theory perspective). This upon release had Ryuga arguably the second best Ike behind Ryo, drop Ike and pick up Corrin ( Ryo is god tier loyalist and will never do so... His Ike rap man). Ryuga then proceeds to beat Ally, and get 2nd at landlocked a stacked tourney with solo Corrin, this prompts a Corrin hype, and allot of top players started to rate her highly... namely ZeRo. So this really made Corrin a target to be torn down , especially due to her being hailed as best FE character by a large portion of the community. Now the opening to bring down Corrin began when immediately after landlocked Ryuga goes on a long hiatus, and won't be back until mid summer after CEO. So Corrin looses its best and only close to top player solo rep. What Corrin is left with is a bunch of mid and high lvl, but no top lvl solo mains. Her regional results remained good with standouts like Cosmos, hakii, Dexter, and others, but she lacks any sort of national lvl rep, and that is the results that most people look at. Now after a couple months of hiatus by Ryuga Corrin has had very few national lvl showings, most of which are not in north america (pretty much none in the US). The current somewhat boiling point kind came with that observation. It's a whole lot of " see Corrin doesn't do well at large tournaments, there are no Corrins in these national top 32's, but hey look there is a well known Ike and Marth! Ike and Marth are so much better objectivity because of this!". Of course in these tournies the fact of the matter is there are no Corrin's of note. We really only have one tourney of note with a Corrin solo main of a known top player, and that ended in 2nd place. It's obviously to early to tell how viable she is, but people act like Corrin not showing up at tournaments in top 32 with no Corrins there is definitive proof she is not viable, when the time a known top corrin main has show up she has done well. Tl;DR Corrin's lack of top lvl solo rep is hurting her perceived viability a ton.