Really, I think we need a measured response to this.
The sense of the self as we perceive it today is relatively recent. It's taken a radical turn with the revolt against institutions that began in response to the Industrial Revolution, and has been rebooted with the emergence of Modernism, Consumer Culture and the US as the driving force after WWII.
A significant element is the philosophy of Relativism. The Stanford Encyclopaedia of Philosophy says:
"Relativism has been, in its various guises, both one of the most popular and most reviled philosophical doctrines of our time. Defenders see it as a harbinger of tolerance and the only ethical and epistemic stance worthy of the open-minded and tolerant. Detractors dismiss it for its alleged incoherence and uncritical intellectual permissiveness... From ethics to epistemology, science to religion, political theory to ontology, theories of meaning and even logic, philosophy has felt the need to respond to this heady and seemingly subversive idea. Discussions of relativism often also invoke considerations relevant to the very nature and methodology of philosophy and to the division between the so-called “analytic and continental” camps in philosophy. And yet, despite a long history of debate going back to Plato and an increasingly large body of writing, it is still difficult to come to an agreed definition of what, at its core, relativism is, and what philosophical import it has..."
For the believer of any ilk, Relativism attacks the idea of objective reality and Eternal (or Transcedent) Truth. Not only the claims of the Abrahamics, but of every religion — Buddhism, for example, is undone when one realises The Four Noble Truths are relative, contingent and thus negotiable.
So although love oneself may well be implicit, as texts are contextual to the sitz im leben and there is ample evidence that man has never been so self-centred and self-regarding as we, the products of a post-WWII consumer culture.
Thus the practice of humility, detachment, self-effacement, of kenosis is regarded as suspect.
There is the telling of the mystic St Katherine of Sienna, in which Christ says "I am He who Is, you are she who is not" — this is fundamental to the mystic path, asserted by commentaries of all spiritual traditions, with the notable exception of many produced in the late 20th century west.
When I turn on my washing machine, it sings a little song. When it finishes a cycle, it sings another. OK, I tell it, but you are just doing what you are supposed to do, there's nothing to shout about ... same with us.
Too often 'love thyself' assumes that I should 'because I'm worth it'.
