Not true. Practicing incessantly will make you excellent in one category. Reading, learning and continually evolving will make you better across several.
I can stick my head in the sand and keep programming PHP, but thanks to the web and reading, I have an interest in design, AJAX, and most of all Ruby on Rails. You can choose to be insanely good at one thing, or just good at several. I'll take the latter since its more flexible.
Being excellent in one thing is often cited as a key factor to success. For example by Google:
www.google.com/corporate/tenthings.html
"It's best to do one thing really, really well"
What insights do you have to proove the makers of the most successful tech startup wrong?
I can stick my head in the sand and keep programming PHP, but thanks to the web and reading, I have an interest in design, AJAX, and most of all Ruby on Rails. You can choose to be insanely good at one thing, or just good at several. I'll take the latter since its more flexible.