And BTW, b4 gimmel tamuz chabadskers weren't just saying that their rebbe is a candidate for moshiach. And for a lond time afterwards.
@Lamdan and others- People didn't make a distinction between chezkas moshiach and moshiach vaday. Everyone did believe he was moshiach. But there is no such thing as moshiach vaday until the beis hamikdash is rebuilt. Just like you say most people don't think about who moshiach is, chabad people before gimmel tamuz didn't think about making a distinction between chezkas moshiach and moshiach vaday. Now that it's a bigger issue and being dissected, it comes out that what everyone besides the tzfatim really believed was he was/is for sure a chezkas moshiach.
This is all tied into what WhyMe pointed out I believe
Why do you insist on equating belief that the rebbe is Moshiach with the belief that he absolutely must be and it cannot be anybody else?
I'm sure you'll claim I'm backtracking and changing the past, and that you know cuz you spoke to people then.
But if you want an answer and I have spoken to people who were there before gimmel tamuz then this will be a satisfying explanation. If you don't want an answer/explanation, then feel free to ignore this post.
ETA- I'd equate before gimmel tammuz beliefs to similar ones of Rabbi Akiva about Bar Kochba. (Who yes was murdered insert diyuk in rambam here;) )