Disclaimer: I run a tech conference called Front Porch. It's a local event that covers a lot of material in front-end web development. I rent a theater, invite several speakers and attendees, and we make a day of it.
Before I started Front Porch, I worked for a company that frowned on its employees attending conferences of any sort. It wasn't a hard, fast rule, but it was the company culture that "you do not attend conferences." It's kind of like the rule that employees can't discuss their salaries. You can't enforce it, it's not even legal, but the boss has gone to great lengths to imply it.
So why would a company try and keep its employees from going to a conference? Is it because they feel conferences are a waste of money? Do they believe conferences have no return value? In this case, it was because they feared their employees would leave them.
What kind of message does that send to the employees? That message tells employees that their company does not value employees enough to further their education. It says that their boss does not trust them.
However, while some companies have this ideology, others actively send their employees to conferences. Tech conferences are a good way to understand the ecosystem of the industry, both locally and worldwide. How have browsers changed in the last year? How has web development changed the mobile marketplace? Which languages and frameworks are replacing others? How does this affect your clients' expectations — current and future ones? What are your competitors doing to stay ahead of the curve (they're probably speaking at my conference, for starters)?
Tech conferences are meant to improve the skills and lives of their attendees. The takeaways from these events are immediately applicable to employees and their teams. By sending your employees to conferences, you are letting them know that you care about their careers, you want them to learn and grow, and you want them to be active in improving your business.
Look, I'm not saying that you should send your employees to my particular tech conference. That would be great, but that is not the point of this article. I began Front Porch from my passion for a healthy, growing industry in web development. I want developers to have the opportunities to learn and grow and feel that they made the right career choice — because they did.