MG Siegler says startups should build for mobile first. More specifically:

Don’t build an app based on your website. Build the app that acts as if websites never existed in the first place. Build the app for the person who has never used a desktop computer. Because they’re coming. Soon.
His basis for this argument is relatively straight-forward:> In the next five years every person on this planet is going to be using a mobile device. And these devices are going to be used far more than any traditional computer ever has been and ever will be.
MG’s advice is really great … if you’re a mobile app company. Otherwise, it’s not the best advice. Yes, startups should position themselves for success down the road. However many of the startups that are funded by even MG may not even be around in five years. If you’re targeting businesses today, you definitely want to build a mobile-friendly service. Yet immediately ruling out web-first as an option is absolutely foolish.

Is mobile faster growing than desktops? Of course, but what percentage of workers in the U.S. still sit in front of a computer every day? Most. Operating as though MG’s assertion that “The PC is over” is accurate, is absolutely foolish. That’s like declaring that email marketing is now dead because there’s SMS marketing. Or a couple of years ago saying that you shouldn’t make your site Internet Explore compatible (it’s still 24 percent of the market despite increasingly becoming “a relic” and being the bane of every web developer’s existence).

There are multi-billion dollar industries still built around “older” distribution channels like desktop computing. More importantly, revenue there is still growing. Are they as sexy as the companies that MG wants to invest in? Probably not, but it’s where the businesses that account for the majority of revenue in the technology industry exist. Just take a look at these projections that Google will still be generating over 70 percent of their revenue from channels other than mobile (primarily desktop) in five years.

I should also add that MG’s own words suggest that you should act as though the web never existed, implying that you should only build apps. That’s also absolutely foolish. Declaring desktop computing and websites dead in a single post is crazy.

Mobile is big. Mobile is great. I love mobile. Mobile usage is growing at an insane rate. Some companies will even see a large percentage of their revenue shift to mobile (like Facebook, eBay, and others). However I’m writing this post on my laptop, and plan on continuing to write posts with this old-school device for years to come. Many of the businesses I know are doing the exact same thing.

If you run a startup targeting businesses you should definitely consider mobile apps-second as a valid strategy.