As a technical person (electrical engineer) that is struggling to learn the business side of things (business school and budding entrepreneur), I echo the comment that there are simply not enough hours in the day to do everything. Furthermore, executing is about forming the right team (meaning they have a diversity of skills) because no one person can know everything. Even if one person did know everything, other things will probably come up in life (i.e. family, personal health) that require a "separate CPU" that can take over the workload, such as a cofounder. Your cofounder's skills should be complementary, but I think it is helpful to have a cofounder that you trust enough and that has enough breadth to keep the ship from running into the rocks if you have to take care of other things for a short period of time.
For myself, I have many more ideas for products or businesses than I have time to fully evaluate, much less execute. Because of this, I have been spending more time talking to like minded people and figuring out ways that I can add-on to existing products or partner with existing companies who have already done some of the work for me to create win-win situations. As a related project, I am working to launch a development/consulting company whose primary activity is to build consumer hardware prototypes and do feasibility studies on new consumer product ideas. There are probably a lot of people out there with promising ideas but who lack the domain experience or business skills to vet those ideas.