See I have a different take on it Beccabop - my opinion is that the actual professional advice (as it is advice from real life professionals) is based on the best information and research available at the time. That's not to say that it is 100% correct and will never change. There is always research ongoing and hopefully the new research will be more targeted and more rigorous than what has gone before and so will give a more robust answer on which to base guidance. But does that mean that there should be no guidance because the information available on which to base it is always changing?
Taking the peanut example, a few years ago there was a strong concern that peanut consumption during pregnancy was linked to allergies and so advice was to avoid peanuts. Subsequent research has demonstrated that not to be the case and so the advice has changed. The alternative scenario is that the initial concern wasn't considered strong enough (or there was insufficient research) and so no guidance was issued. Subsequent research was then undertaken that found there was a connection between peanut consumption during pregnancy and allergies in young children. How many of the parents who now have children with severe allergies would be happy that the information about a possible peanut/allergy link wasn't available and how many would be suing the government for failing to tell them that avoiding peanuts might have prevented them being in this situation?
Listeria during pregnancy can kill your baby.
Toxoplasmosis during pregnancy can kill your baby.
Some life choices (be it eating mould-ripened cheese or pate, or emptying the cat litter tray) can increase your chances of catching these infections. The risks may be small, but they're there. I don't think its reasonable or rational to say that following professional advice is "pointless".
IMO a bigger problem is that we, as a nation, are very bad at understanding risks and so the advice is presented as a lists of "does" and "dont's" with no context and no quantification. For me, as an individual, I'd rather know why this particular item is advised against, what the risks are, how big the risks are, what the possible consequences are and the make my own mind up. But then not that many adults in the UK seem to want to accept the responsibility that comes with making decisions like that.
I do believe that the guidance that is in place is put there as a framework to try and maintain the health (and save lives) of the general population. I do believe that its updated reasonably often as new research becomes available indicating that the guidance in place is no longer robust. You may choose to see that as a weakness - I choose to see it as a strength. I don't believe that following all guidance blindly is a sensible course of action - but I do believe that discounting it all without understanding why it is there in the first place is dangerous and misguided, and that seems to be your position, and a course of action you are recommending others follow. And that frightens me.