Heavy people are better off with wide tires. I only ride mountain bikes and fat bikes.
That may be your preference but the wide of the tire has little to do with the strength of the wheel. Everyone dances around the real issue when it comes to broken spokes. They blame the tires, the rim, how the bike is ridden, etc. but they never address the issue. If the spoke breaks, it’s not because the tires are too narrow. The spoke breaks because the spoke isn’t up to the job.
Spokes don’t break because of impacts. The shock of the impact is certainly lessen by the tire but the shock of an impact doesn’t really drive up the spoke because of how the spoke and rim interact. The rim is held in place by tension. Impacts cause the rim to ride up the spoke but it doesn’t hit the end of the spoke. Even if you were to buckle the rim, the spoke only becomes loose. It doesn’t see any compression.
The real reason for spoke breakage is not the “up and down” movement of spokes but the natural bending from side-to-side movement of the spoke as the bicycle moves down the road. The very act of pedaling causes the wheel to lean one way and then the other. The spokes experience this as a bending out of plane force which stresses the bend and starts to fatigue it. The more bending and the larger the magnitude of the bending, the more stress on the spoke.
If you put more meat at the point where the spoke breaks...i.e. the elbow...the spoke is more able to resist that bending. Increase the spoke diameter by 0.3mm (from 2.0mm to 2.3mm) and the strength increases by 32%.
Ric Hjertberg says that it’s the equivalent of adding 10 spokes. That might be an overstatement but my own experience says that it’s at least the equivalent of going up to the next hub drilling. In other words, using the 2.3mm spokes on a 36 spoke wheel is at least the equivalent of going to a 40 spoke wheel.
I ride mountain bikes with 2.2” tires to road bikes with 23mm tires and other sizes in between. I’m not worried about breaking spokes because of the width of the tire. I build wheels based not on the strength of the rim, hub or, for that matter, tires. I build them based on the part of the wheel that does the work.