Essentially the design and development phases are merging and if you’re naturally good at design and front-end development you will take to designing in the browser like a duck takes to water.
One major benefit of designing in the browser is that we can design based on realistic expectations. Sometimes designing in software can create unforeseen problems for front-end development. UI elements could be designed wonky or maybe they just don’t make any sense, it’s hard to explain to a client why you changed something, not because they won’t understand but because you’ve already pitched it in the design and had it approved. Designing in the browser lends itself to the idea of simplicity.