It presupposes so much. The statements are probably designed to make it look as if FPTP is the problem here by referring only to minority/majority of turnout. It is a problem, but we know turnout is usually not that high, so even if we had a form of PR, all parties would still be elected by a relatively small proportion of the electorate - possibly even a minority. So even with PR, for the same level of turnout, we'd still end up being ruled by those voted for my a minority.
I agree we should be moving to a form of PR, but, I suspect, for reasons different to those that coffee might have.
There are three fundamental questions for anyone advocating Brexit:
1. What, precisely, are the significant and tangible benefits of leaving the EU?
2. What damage to the UK and its citizens is an acceptable price to pay for those benefits?
3. Which ruling of the ECJ is most persuasive of the need to leave its jurisdiction?