Just because a general dentist takes a lot of continuing ed doesn't mean they don't refer. My husband are more than happy to refer. We do do a lot of endo, but we refer a lot to. We do some extractions, crowns/bridge, cosmetic dentistry, intial peridontal therapy and place crowns on implants. We not place the implants. We refer to oral surgeons, prosthodontists, periodontists, orthodontists and pedodontists too. We do not do general anesthesia, conscious sedation, not even nitrous. We keep it pretty simple.
Even to do what you learn in dental school, you need a lot of continual educational support. Talking to other dentists at meetings is refreshing also. If you're in a small office, most days the only interaction you may have with another dentist is limited to discussing a case you referred to a specialist.
Sometimes refering is good even if you can do the procedure. If you are heavily booked and a patient needs a root canal, a specialist may be able to accomodate the patient within a better time frame. Your patient will be back to you for the post and core and crown and will appreciate that you helped solve their pain problem.
A general dentist in a rural area may need to become proficient in more areas. Continuing ed in endo or oral surgery may serve his patients well.
After doing the required restorations, crowns, simple extractions and root canals in dental school, there is still a lot to learn. The older and more experienced you get, case selection gets easier because you know what you enjoy doing and your educational limits. Refering is a very good thing and so is continuing education.