My view is that they solved voice communication first - that was their original use case. Reliable multi-party voice is a harder problem than text chat and mean

My view is that they solved voice communication first - that was their original use case. Reliable multi-party voice is a harder problem than text chat and means that you can't/don't just rely on Electron for everything. Their product is a way to 'sell' some good non-trivial (but not groundbreaking) engineering. Whereas Slack is successful because it understood it's usecase well (including how to sell to enterprises).