They perform comparatively slowly and use more resources and battery power.
For example hexchat an irc client seems to use about 50-60MB of ram.
Slack by contrast out of the box appears to use 1.2GB of memory. There are at present 12 applications open on my machine. If they all used over a GB each something would be starving given that I only have 8. Note please that most machines still have 8GB or less.
Do you really not understand why people are biased against electron or are you pretending to for effect?
I just wanted to hear what people had to say to be honest. Given the success of Slack, is it really that bad? Why has no resource "friendly" alternatives taken its place?
Because people used to be able to use whatever IRC client they wanted for Slack, so it wasn't a problem if they were too memory constrained. In a pure embrace, extend, extinguish fashion, Slack closed the gateway that made them popular and now everyone is stuck with their pile of crap app.
With electron, you're running a full chromium at the back end for any task. This increases memory and CPU consumption a lot. Atom consumes as much as RAM as Eclipse for example. Also it's slow due to this load it creates.
For simple tasks, a full fledged, programming capable text editor can fit into ~60MBs. Atom needs 660 just at the start. With that amount of RAM usage, I even cannot open large files as reliably as vim for example.
However, it's all static HTML. An HTML rendering library will use less CPU and RAM than a full fledged web browser, and will be much easier to maintain.
Calibre's e-book reader uses ~100MBs when opened. It runs independent of the main Calibre app, in its own process. Again, an Electron app will be heavier here.