Actually, there is a single technological advance responsible for electric's proliferation- LiPo. Before this there was no way to pack enough battery onto a 1/8 car and get it to run for more than 4 minutes (and it'd be a tank).

Nitro has gotten better. 10 years ago it was really hard to get an engine to run reliably. Even now that it's easier, it's still a PITA. I ran it for 5 years and liked it a lot but in the end I realized that electric 1/8 would be just as fun without the headaches.