It prevents people from forming their own opinions about x, just because some other people already made an opinion about something similar.
Strictly speaking, no. A truly rational person is capable of forming his own opinion on the bases of his morals and the rules of logic. That person never allows the consensus to dictate what his opinion should be.
Regarding the application of law, when enough people (or lobbyists with enough influence) form an opinion which is at odds with the legal precedent, they can prompt their legislators to enact or amend laws that overrides that legal precedent.
If abused it can mean that the particularities about this specific x are ignored.
Yes, and unfortunately it happens in courts. However, such instances are more a product of judges' illicit interests than a genuine consequence of the bandwagon fallacy.
Some (or perhaps many?) courts in the U.S. go to the extent of blatantly distorting the evidence and the record on appeal so as to rubber-stamp the inept findings of lower courts and thus force an outcome which contravenes the law. This happened to me, and since then I take with a grain of salt the "factual background" of any court opinion I read.
Lawyers will typically deny the courts' deliberate ignorance of the proved facts for three main reasons:
- An acknowledgment of that sort hurts the commercial interests of the
legal "profession" altogether. People will question "why hire a
lawyer and go to court if my case will be decided arbitrarily
anyway?".
- A lawyer is less sensitive to judicial distortions of the evidence
than the injured persons themselves. After all, the lawyer is handling simultaneously, and he would rather not get
under the judges' skin for fear of being essentially blacklisted in judges' chambers.
- Judges might be more tempted to distort the facts of a case where the
injured party is a pro se litigant than where a lawyer represents
that party. They simply calculate that the pro se litigant will
hardly devote serious effort to denounce elsewhere the judicial
unfitness.
Thus, the easy and comfortable thing courts do is maintain the oftentimes false and misleading appearance of their "consistent" abiding by legal precedent.