100kg-125kg (220-275lbs) are fairly common weight ratings yeah. Half of it is because the frame needs to handle you dropping a curb without snapping like a pretzel, but the other half is because gravity is a bitch and trying to go up even a small hill takes a lot of power.
Most escooters promise 25-30% climb capability, but hauling 300lbs up a 30% grade at just 10mph requires 2200 watts, while most smaller escooters max out at 500-1000W.
Even that 1000W is only enough for ~4.5mph.