End of the day, what makes a startup successful is customers. What customers care about is whether you solve their problem and bring value.
One of the ways that startups like to attract dev talent is by saying how cool they are - the latest fad, the latest stack and free snacks. But that's not what people care about. So, focus on solving their problems and not what your platform is.
I find the question valid. Many tech people would think on the back of their mind that this startup is not cutting-edge, doesn't have a great dev team etc. Not that I am a PHP hater. Your nickname suggests that you use a PHP-based CMS. That doesn't sound cool for a startup ;)
One of the ways that startups like to attract dev talent is by saying how cool they are - the latest fad, the latest stack and free snacks. But that's not what people care about. So, focus on solving their problems and not what your platform is.