Sounds like more of a complaint of informal instant messaging in general, rather than a problem specifically attributed to Slack.
Slack has it's problems, but it also has it's place.
For the Slack teams I'm a member of, we've got rules about using @channel and @here, and anybody that uses either is usually shamed to some extent if they do so.
For the complaint about the use of Electron (and all of that overhead), it's trivial for a Slack team to enable the IRC gateway (in /admin/settings#gateways) and connect through your preferred IRC client.
Slack has it's problems, but it also has it's place.
For the Slack teams I'm a member of, we've got rules about using @channel and @here, and anybody that uses either is usually shamed to some extent if they do so.
For the complaint about the use of Electron (and all of that overhead), it's trivial for a Slack team to enable the IRC gateway (in /admin/settings#gateways) and connect through your preferred IRC client.