Whenever a single party cannot obtain a majority then minority parties will carry influence out of all proportion to numbers who voted for them. That is dangerous enough, in that there is a risk of the will of a minority overturning the that of the majority, but it is something we have to live with.

At least most of the minority parties, be it the Lib Dems, the Greens, UKIP etc claim to have the interests of the whole of the UK at heart. The difference with the SNP (and to a lesser extent Plaid Cymru) is that they do not.