Cameron was a disaster. Austerity was incredibly cruel on the poorest of the population, and the UK wasn't exactly a shining light in its recovery from the financial crisis. He led a weak remain campaign and then stepped aside as soon as Brexit became difficult, and the following governments have had to deal with his mess, the covid outbreak and the effects of the war in Ukraine.
So I think you could equally say that the coalition is a root cause of many of the issues of today. That and the lack of any credible opposition for years.