Many startups tend to keep the employees (usually devs & designers) focussed too narrow, never letting them expand to other roles, or keep them doing everything (usually non-tech employees/founders), without giving them time, resources or backing to develop expertise in one area.
I believe that there are no strict job descriptions or siloed roles in a startup – everyone does everything, at least some of their time. And it’s all for the better – of both the enterprise and the individuals. Everyone learns & grows, faster.
However, experience tells me that starting your stint with a specific role or project greatly improves the chances of a successful on-boarding. A specific project lets the new joiner do a deep dive and learn quickly about one specific area (become go-to person for that small, specific area), show some deliverables (thus earn cred in the new team), while also learning about rest of the roles (to get an idea of where they want to grow/expand).
Once a bit settled, more roles and responsibilities can, and should, be added. Not letting employees expand beyond their early roles, is just as bad as getting them to work on *everything* from the moment they step on-board. You never know, that backend dev could have evolved to become the best product manager or business development manager money could ever hire.
My life example: One97 versus ActiveMedia
Successful enterprise example: Automattic