It's easy to get caught up in the latest great programming language or framework but a start-up shouldn't be concerned with that. The majority of these latest programming languages/frameworks come from big corporations like facebook/google with huge tech teams so not relevant to most start-ups. A start-up wants something tried and tested that will allow them to move quickly and compete against bigger development shops. Having that underdog mentality is important as it makes you focus on your strengths and try to leverage them as much as possible. As the web is becoming increasingly faster and more standardised there is no reason why web technologies can't be leveraged to meet the majority of the business needs. Using a development framework like Ruby on Rails is perfect for that. Thousands of successful start-ups have used it as it promotes using proven practices to be as productive as possible.

A start-up I worked for recently didn't have the funds to build an IOS/Android application as there are considerable time/money/resources involved with that. So the options are to raise more resources or somehow work with what we have. I recommended and implemented wrapping our existing web application in an IOS/Android shell and using the web UI to run within the native application. This wasn't perfect but met the need of the business quickly without any big expenditure. It was a very low risk option as had it failed the consequences was only a small amount of time lost, no big deal. Any time we now make a change to the codebase it's instantly replicated across the web and mobile applications instantly. No complicated/costly release process for the difference platforms. This solution met the business needs at the time, its not what standard industry practice would recommend if you asked around. Every situation is different for each business, not a one size fits all approach.