Our experiences as people contribute to our writing, yes. But our experiences writing contribute to a very narrow spectrum of experiences, and ones which are accessible primarily to other people who write. The process of writing, and the things we think about as related to writing, speak most loudly to writers.
But our range and depth as writers is greatly strengthened by observations of other facets of life, and a broad range of experiences. Nora Roberts, for example, includes neat things about flowers in her romance novels, which adds depth to characters who are florists. Tumblr user CeruleanCynic writes adorable romance through the medium of two characters answering questions about disasters. Both writers, though their research shows to varying degrees, have their writing enriched by outside interests.