Not all specualtion is welcome..some is just ridiculous. .
I mean, sure, Ishiyama did play us for a fool by hiding so many titans right in front of our noses without us realizing, but that doesn't mean that everyone else can/has to be a titan.
I think that I saw a 'he is a titan' theory for EVERY single major character in the past half a year or so..and it's just plain ridiculous.
Same with the people specualting who the Ape titan could be (annie's dad, grisha, levi?!), I mean wtf..just because it turned out that infamous collosal and armored titan turned out to be someone we already knew all along, it doesn't mean that every other shifter has to be someone known as well.
And even in the latest chapter with the reaperance of the titan that ate Eren's mom I saw a bunch of theories about it being Armin or even Moses (Brown in manga)..It's just..I don't even...