Oh I would absolutely encourage anyone who wants to be involved in web to try their hand at either, but if worse comes to worse and they don't find themselves particularly cut out for them, design tends to be the one that they stick with because it's easy to look like you produced "something" and there's always somebody out there willing to buy "something" if the price is right.
Having watched a few people struggle to the point where they are switched off of projects regularly and haven't left a job on their own terms, I think it is worth acknowledging that the allure of working in this/any industry may outshine one's passion to do so and it may be healthier to find greener pastures than to settle on the one that's "good enough". There are also a lot of auxiliary roles to designers and developers that they may find a lot more fulfilling and that give them the opportunity to learn over time.
Having watched a few people struggle to the point where they are switched off of projects regularly and haven't left a job on their own terms, I think it is worth acknowledging that the allure of working in this/any industry may outshine one's passion to do so and it may be healthier to find greener pastures than to settle on the one that's "good enough". There are also a lot of auxiliary roles to designers and developers that they may find a lot more fulfilling and that give them the opportunity to learn over time.