There's a pragmatic reason and a serious reason: 1. Pragmatic: you don't get tenure for publishing to your website. 2. Serious: peer review, despite its flaws

There's a pragmatic reason and a serious reason: 1. Pragmatic: you don't get tenure for publishing to your website. 2. Serious: peer review, despite its flaws, is a crucial safety check in science and it's not wise to side-step it.