The logic of the idiom is beautifully straightforward: 应有 (yīng yǒu) means “what one should have,” and 尽有 (jìn yǒu) means “all of it is had.” Put together, it literally translates to “What should be there, is all there.” This creates a powerful image of perfect, curated completeness.
This idiom is extremely common in both spoken and written Chinese.