Aside from MAYBE added heat to the blade from sawing hardwoods at an increased ft-minute of speed, I think that the blade fatigue from using 19" dia. pulley-wheels, on most mills is the reason to keep the speed down. It's a compromise for the factory, to keep the blade speed to where fatigue isn't happening sooner and getting lesser life out of the blade.
You hear a lot of talk about blades breaking, whether in the welded area or in the gullet. If one keeps the gullets ground clean of micro cracks, one uses up the blade faster by grinding away metal increasing blade sales for the dealers-manufacturers.
We built a mill using 24" outer diameter trailer wheels-tires. In over 200,000 bd'ft sawn, we never broke more than a couple blades. That was due to operator error, not blade fatigue.
