- can't (realistically) use an alternative runtime. You are stuck with the JS ecosystem.

- can't start when the OS starts

- can't integrate with the UI (task bar, explorer menu, etc)

- can't run a server in the background for native perfs (like most electron apps actually do)

- can't open a server or a communication bus to allow apps cooperation, or playing well with the OS

- can't access the file system in any meaningful way to provide any kind of scanning ability

- can't store data reliably, or in any reasonable quantity

- can't call other local apps, run commands, etc

- can't access local libraries: so you do the crypto, hashing, dataprocessing in pure js

- can't access any non standard peripherics

- can't use the network, forget about avahi/bonjour, broacasting, capturing packets or doing CORS