The difficulty is, what happens when it's not something (mostly) harmless like
Fate/Kalied Liner Prisma Ilya 2wei, it's
A Serbian Film or some snuff movie? The BBFC's current existence is mostly as the easiest and most efficient way for the government to enforce the Obscene Publications Act and provide a helpful guide to parents.
And that later one is probably more important than you'd think, the visual styling of anime often makes it look more childish than it actually is. The marketing for
Assassination Classroom does not exactly indicate that the show would include an implied sexual assault and some sex and drug references. Nor does
Yowamushi Pedal's marketing suggest it includes a scene of substance abuse (played for comedy). Both, for my money, look rather like Cartoon Network shows. Just because we are all adults, capable of making our own informed decisions, doesn't mean everyone is and the BBFC's relatively dependable guidelines and classifications provide a good guide for helping parents who might not be able to make such decisions. (I won't defend their "potential to harm" cuts though, those are ********.)
Whilst true, your comment about streaming services ignores an important fact. Both Amazon and Netflix already submit their original content to the BBFC voluntarily, and where possible use BBFC ratings within their streaming services. (Though Amazon doesn't seem to do it with it's anime originals for some reason.) The BBFC has no need to push for legislation within this field, because the important parties are already doing so. Parents view the BBFC ratings as understandable and trustworthy, so streaming services are using them voluntarily as a sort of badge to demonstrate that their streaming service is reliable and trustworthy too.
And according to their podcast, they looked at reducing their fees for indie distributors and charging more to majors to cover the difference. Unfortunately, the government told them they had to get the approval of
all stakeholders, and obviously nobody would agree to pay more, so they were a little bit stuck there.
Finally, as a matter of personal curiosity, may I ask if you are from the UK ,
@Lord Bacchus? The tone of your questioning leads me to think not, but then I wonder what the relevance of it is to yourself.