If he was talking about '[visual/user-interface] design' and '[algorithmically/architecturally-scalable] development', I could see there being a tangible tradeoff in acquiring expertise. Effort spent on one may offer little spillover benefit for the other, meaning larger returns to specialization.
But '[visual/UI] design' and 'front-end development'? I'm perplexed that so much of a culture of splitting these roles has arisen. In my mind they overlap so much that enforcing a formal division, in either process or the recognition of 'expertise', introduces wasteful mismatches of expectations and cost/value estimates. That is, the dividing "fence" you say your career has been straddling shouldn't even exist.
The cynic in me thinks the advice you've received, from the boss and 'people from both camps', has been more about them defending their traditional turf and comfortable silos than what you should do to be 'excellent'.
But '[visual/UI] design' and 'front-end development'? I'm perplexed that so much of a culture of splitting these roles has arisen. In my mind they overlap so much that enforcing a formal division, in either process or the recognition of 'expertise', introduces wasteful mismatches of expectations and cost/value estimates. That is, the dividing "fence" you say your career has been straddling shouldn't even exist.
The cynic in me thinks the advice you've received, from the boss and 'people from both camps', has been more about them defending their traditional turf and comfortable silos than what you should do to be 'excellent'.