First, I think that was partly
answered on this blog by Matthew:
"A historical Jesus explained the most data with the fewest assumptions and unanswered questions."
and also, on Clarice's own forum (JesusMysteries) by GR Gaudreau:
"I've been thinking a lot about Occam's Razor lately, and when I see all of
the complicated twists and turns some have to take to explain why Jesus
didn't exist, it just sours the cream for me."
As a non-believer, non-religious, non-Christian, yes, I am ashamed that some other atheists go into all kinds of far-fetched & ill-evidenced theories in order to sketch the beginning of Christianity with no HJ.
But I think these "absolutely_no_HJ" theories are largely motivated, not only by anti-Christian feelings, but also by disgust of HJ descriptions. Even when some of them come from non-believers like Dr. Ehrman, expurgated from divine and extraordinary stuff (but still with a HJ as a charismatic teacher & the real founder of a sect/movement/religion), they are nevertheless about a near-Christian HJ (but false, according to my studies). Therefore they compel non-believers to adopt or create no-HJ schemes as the only perceived options away from these HJs and Christianity. And because what they see in the box jumps at them as being unacceptable, they look outside of it for solutions.
I feel bad that my option of an ultra minimalist HJ, NOT a teacher, NOT charismatic, NOT the creator of Christian beliefs, is not often considered, and barely known. However, it does explain the lack of external evidence, the many silences from Paul (who nevertheless made important statements about an earthly & human Jesus) and the so-called messianic secret in gMark, among many others things.
But that “nobody Jesus”, even as a poor uneducated Jew with short-lived local notoriety but executed and mocked/charged as "king of the Jew", was likely to start a new sect after his death. Why? Because of the immediate historical/political context. The rest came through the later use of out-of context OT bits as authority, claimed revelations from above, Philo's works, etc, all of that generating myths. And that was only the start.
Then why is this ultra minimal HJ not proposed more often?
I see several reasons for that:
a) People are not likely to believe that something big (like Christianity) started from somebody small. They think either the whole thing had to include a charismatic founder or that HJ (as the great gospels-Jesus) was totally invented.
But we have the example of Rosa Parks, a humble seamstress, who by a simple act eventually originated the Civil Rights Movement (led by others from the start). And on the bad side, there is Gavrilo Princip (heard of him?) ...
b) “historicist” scholars would be most reluctant to embrace that kind of HJ, many because of their faith, others because that would be against their own past education & writings and the whole scholarly tradition. Even Dr. Helen K. Bond, whose views on HJ are close to mine, still kept HJ as teacher with some education in her book "The Historical Jesus: A Guide for the Perplexed".
c) This HJ cannot please most Christians and activist non-believers (who are looking for a more final solution).