No, a bone graft is not necessary in every extraction. As a matter of fact most extractions, especially when there is a nice wide ridge do not necessitate a graft. Bone graft will often slow down the natural healing process of a socket. Over the past 30 years many advancements have been tried in Implant Dentistry, we have gone through immediate grafting, immediate implant placement Etc. At this point most top specialist will tell you that it is always better to perform one miracle at a time. No implant system or dentist are perfect, neither are our patients. Every time you try and cut a corners you might face consequences. Just follow the KISS principle: keep it simple stupid. Talk to your surgeon, sounds like the person knows biology and is probably doing it right.