Industry associations exist to serve their members' interests, but I can't see why they should be criticised in this case.
According to the FAO, there were 6,169,000 tonnes grown in the UK in 2005. According to Wikipedia
In 2008 The Guardian reported that 330,000 people held an allotment
If the average such allotment holder had a similar success to me, and lifted 20kg (I just weighed them), that would be about 1% of the commercial crop. I really do not think they have anything to fear from this - in fact, they are likely to benefit from increased interest in the different varieties of potato out there - I notice we see more in shops now.
How much more likely is it that this is a real issue? Why otherwise would two national organisations chose to work with the Potato Council
The Potato Council is working with the Royal Horticultural Society and the National Society of Allotment and Leisure Gardeners (NSALG) to produce a special blight fact sheet and educate gardeners about the disease.
Do those automatically attaching the Potato Council not know that there are significant variations in blight resistance? In the best known case of potato harvest failure - the Irish Famine - the reliance on one particular blight susceptible variety was a major factor, as well as the weather. It's not unreasonable to suppose that older 'heritage' varieties are more vulnerable - it could well have been part of why they aren't grown so much.