Those are related. Part of what makes engine-powered VTOL difficult is the engines. The V-22 Osprey has two propellors and two engines, but in order to handle an engine failure, there's a complicated driveshaft and gear arrangement across the middle of the aircraft to send power from the working engine to the other propellor. I don't know that anyone has seriously tried more than 2 engines for a VTOL system.

Electric power allows you to have lots of small fans, a few of which can fail without disaster.

Also, throttling turbines up and down fast enough to stabilize an aircraft doesn't seem to work well.