“Why are people so obsessed with this?”
The issue even has it’s own wikipedia page!
Sorry, no links
In my ignorant open-minded not-so-frum opinion its controversial because if it was an “official” position that the Rebbe is the mashiach it would cause Lubavitch to become a new splinter religion like one of many splinter groups that have their origins in Judaism. (See Besalel’s comment.)
The biggest difference between Judaism and Christianity is accepting “you know who” as the messiah. As a Jew who grew up among way too many Christians, when religion came up, I was often asked about this. They could not understand that ‘he’ had no place in our religion nor my headspace.
Between the different groups within Judaism today the major differences are all generally based on religious practices not theology.
I’ve only seen the topic discussed when Chabad is brought up, not just as a casual conversation.
But I was regretfully warned off of Chabad growing up because of it. I went to a shabbos dinner once at the request of a friend but that was my only involvement. I heard various comments from people I personally respected (not really frum but religiously knowledgable individuals) like, “what’s the closest religion to Judaism that’s not Judaism? -Lubavitch” and “they aren’t really Jewish due to their belief in the Rebbe as Moshiach.” Having no personal experience with or understanding of the group myself, I had no way to evaluate these statements on my own (this predated wikipedia). Recently I’ve been feeling unfulfilled, looking for more religiously (hence me hanging out in the CR), and searching for a new “Jewish home.” Very recently I realized that Chabad checks all of the boxes I have been looking for so I plan to really explore what they offer. There are limited choices for observant Jewish experiences where I live and I am quite thankful for the opportunities they provide.