The cover letter for the documents has a Palo Alto address on their ivory 25% cotton linen 20 lb. bond paper letterhead with custom firm watermark.
In all seriousness, the firms in SV (and NYC area as well) are generally going to be more experienced and connected to deal with the specific issues faced by start-ups, tech companies, and VC funded companies, just to name a few. You don't have to be a lawyer to get the articles of incorporation from the secretary of state's website and pay the filing fee, but the experience in knowing what other advice to give or other documents that need to be prepared, or at least planned for, for your specific industry, stage of growth, and other fact specific situations is not something you can learn through Quora, the secretary of state, or a general law firm that provides formation/incorporation services. Start-ups deal with all different legal issues such as federal and state intellectual property law, securities law, general corporate law, contracts, finance, asset protection, exit planning, officer/director protections, shareholder issues, and capitalization structuring for future growth/capital raises.
If you are just a mom and pop grocery store with 1 small store and no plans to raise money, grow, or be acquired, you may not need a specialized firm in SV to incorporate (although the firm you hire should still go over things like buy-sell agreements, succession planning, asset protection, and required corporate procedures or best practices). However, if you are on Quora asking this question, you are probably in the category that could use a specialized start-up type firm. The majority are located or at least have an office in SV and/or NYC (or surrounding communities/states), but there are certainly all kinds of qualified firms/lawyers that also have the experience that may be needed.
Be an educated consumer and learn what you may need to be sure whoever you hire has experience in those specific areas. If they don't ask detailed questions about your business and future plans with recommendations based upon your answers, they probably don't have the experience you may need.