I disagree.
A good idea will stand on it’s merits; a bad idea will fall by the same measure. Considering the intelligence of the average person* I don’t think popularity is worth much of anything. But I’m curious, if I started a poll and more people agreed with me, would you change your mind? 
*and remember, by definition half of them are dumber than that!
Ideas should stand on their merits, not the number of people who are proponents of it. In that sense, it really shouldn’t matter if one person is a proponent or everyone BUT one, there’s either a good solid logical argument for it it or there isn’t.
However, that it is a logical fallacy doesn’t mean it isn’t potentially useful. All a logical fallacy is really saying is that it doesn’t necessarily follow. After all, there is also the principle of the wisdom of crowds, and it operates exactly on the very same priniciple of this fallacy. The difference is that the wisdom of crowds isn’t a guarantee. By this, I mean saying “X is a popular idea, therefore X is true” is logically flawed; but if I say “X is a popular idea, it may have some merit” is a reasonable statement.
And even when using the wisdom of crowds, the thresholds you set need to be taken in context. Polling the general public on issues that require specialized knowledge can be misleading. You can find a number of people that believe in all sorts of things, like moon landing hoaxers, 9/11 truthers, lizard people, whatever. But when you get into populations that have specialized knowledge about those fields, the wisdom of those crowds is a much better indicator.
Really, when you think about it, this is what democracy is based on. It’s the idea that a lot of people are likely to converge on a good answer, not a guarantee that because a majority voted for something that it’s definitely the correct solution.
I am not a religious person, but I strongly suspect that the goofball beliefs I alluded to are not a part of Judaism. :dubious:
No, they shouldn’t. Their right to believe them should be respected, but there’s no reason to respect creationism or transubstantiation or other equally ludicrous beliefs.