You're forgetting about Apple and that entire ecosystem.
replyAndroid, too. Not much Electron to be found there. Both Android and iOS were heavily optimized for low memory environments back at the start.
First-party and lovingly-crafted indie apps do use native technologies, and often care about performance, but it feels like everything else uses various bloated cross-platform frameworks.
replyThe fact that nothing on my modern day iPhone feels any faster than my iPhone 4 did, when the current phones are 10x more powerful tells me that developers consistently spend >= 100% of the yearly Moore's Law dividend on framework bloat, spyware, and useless animations. If we could run iOS 6 and its matching apps on modern hardware, and set animation duration to 0 like jailbreaks used to allow, imagine how fast our phones would be!