Onlays as alternative to crown

I believe that we, dentist, cut too much sound tooth structure away on daily basis. "Large filling, no problem, we will put a crown on it." "Filling keeps coming off or breaking? let's put a crown on it."
"Broken tooth or filling? let's crown it"
Teeth are not like hair or nails, it does not grow back after cut.

I made this onlay (lava ultimate) with E4D, cemented in the same appointment.

Tooth #30 had a deep O composite, fracture lines on D and mid-lingual.

Occlusal composite removed, crack line at the base of DL cusp.

Caries detector used, and the finished restoration only covering DL cusp, and D marginal ridge.

Buccal cusps and ML cusp are all kept as untouched. Did not extend margins beyond old composite.