I think it’s a bit disingenuous to give a long, vague treatise on crackpots in response to an actual human being, without directly addressing them.
"The suppression of uncomfortable ideas may be common in religion or in politics, but it is not the path to knowledge, and there's no place for it in the endeavor of science. We do not know beforehand where fundamental insights will arise from.... Fundamental insights can arise from the most unexpected sources." - Sagan
There is a reason no one that is respected talks about these "crackpot" ideas. The established ideas are here because they survived decades of trying to be proved wrong but they survive since they fit observed nature. New ideas are just that: new.
When someone introduces a new type of database HN doesn't say "why won't people take new ideas with an open mind??", they say "SQL works and has been proven. You have to prove your new idea is better before I'll use it."
Exact same concept.
There are crackpot ideas tightly knit to a group identity like anti-vaccinations, flatearth, and so on. One way to identify crackpots is to look at the idea and figure out is it's presentation more like your CS 101 / physics 101 etc course or some nice respected physics paper, or more like one of the known looney scenes - flatearth, antivaxx, Meyers Briggs, Scientology etc.
Then there are the lone looneys.
If you don't know what they are talking about - at all - it's best to do some cursory education in the field using some or the other open university resources.
So, rule of thumb - look what an anti-vaxx scene looks like, look what a physics basic course looks like, and figure out is it more like one or the other.
Stuff that looks like some other looney stuff usually is looney stuff as well.
Saying looney for a looney is completely different from disregarding new valid ideas.
An example of a borderline case is the 'reactionleas thruster' they've been testing around the world. It would be awesome if it worked. It's a new idea, goes completely against physics. But it's has sufficient testing data to at least merit a second look by third parties.
"Wegener's theory drew from geology, geophysics, zoogeography and paleontology. It also drew the wrath of scientists from these disciplines. These reactions eventually shut down serious discussion of the concept."
One funeral at a time.
Or not. "Science advances one funeral at a time."
Related HN discussion from a few days ago: https://news.ycombinator.com/item?id=21911225
“A new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows up that is familiar with it.”