People with such attitudes are usually very helpful and worth a lot. They never say “I cannot do it”, they always say “I can do it or I will learn how to do it”. I try to be like that, too. I’m the DIY type of person and try to learn whatever needs to be done. Actually, this is also the way I learnt all the things I know about Linux. Years of hard DIY work, being alone in front of the PC and trying to get things to work. Just like everyone else, there was a time, when I struggled to accomplish my first apt-get install command… 
Many of those “I cannot do it” people are often too arrogant to do something they are not paid for or an expert in. They are too afraid of looking like they are stupid, after all their arrogant behaviour implying they are so smart.
Just recently, I read about a fine example regarding such type of “I cannot do it” person…
It’s just a matter of attitude. If someone is a “I cannot do it” person, there is not much to expect in terms of performance or innovation.